Method of producing a flexible thermoelectric device to harvest energy for wearable applications

ABSTRACT

A method and/or apparatus of energy harvesting for wearable technology through a thin flexible thermoelectric device is disclosed. A lower conduction layer is formed on top of a lower dielectric layer. An active layer, comprising at least one thin film thermoelectric conduit and a thermal insulator, is formed above the lower conduction layer. An internal dielectric layer is formed above the active layer, and contact holes are drilled above each thermoelectric conduit. An upper conduction layer and upper dielectric layer are formed, connecting the thermoelectric conduits in series. The resulting flexible thermoelectric device generates a voltage when exposed to a temperature gradient.

CLAIM OF PRIORITY

This application is a Continuation-In-Part application of U.S. patentapplication Ser. No. 14/711,810 titled ENERGY HARVESTING FOR WEARABLETECHNOLOGY THROUGH A THIN FLEXIBLE THERMOELECTRIC DEVICE filed on May14, 2015.

FIELD OF TECHNOLOGY

This disclosure relates generally to energy production, moreparticularly, to energy harvesting for wearable technology through aflexible thermoelectric device.

BACKGROUND

A thermoelectric device is able to directly convert heat (i.e. atemperature gradient) into electricity. If their efficiency may beincreased and the operational temperatures reduced to near roomtemperature (300 K), thermoelectric devices may begin to supplement oreven supplant traditional power sources used in wearable or internet ofthings (IoT) devices. High thermal conductivity with lower electricalconductivity may prevent higher efficiency. Unfortunately, there are nosingle materials that possess simultaneously higher electricalconductivity and lower thermal conductivity. Low efficiency and highoperating temperatures, combined with higher cost, prohibit currentthermoelectric devices from wider market adoption.

Low efficiency may relegate thermoelectric devices to a few applicationswhere their simplicity and ruggedness may outweigh the inefficiency,such as sensors and waste-heat-energy converters. The current marketproducts are often used in conjunction with either heat sink or activecooling at high temperatures for industrial use cases. Additionally, thecurrent state of the art thermoelectric devices are rigid and bulky, andare produced using complex processes which scale poorly, resulting inhigher cost. As a result, current thermoelectric devices, beingexpensive, inefficient near room temperature, rigid, and bulky, are lessthan ideal for use in wearable or internet of things (IoT) devices.

SUMMARY

Disclosed is a method of producing a flexible thermoelectric device toharvest energy for wearable applications. It will be appreciated thatthe various embodiments discussed herein need not necessarily belong tothe same group of exemplary embodiments, and may be grouped into variousother embodiments not explicitly disclosed herein. In the followingdescription, for purposes of explanation, numerous specific details areset forth in order to provide a thorough understanding of the variousembodiments. Accordingly, the specification and drawings are to beregarded in an illustrative rather than a restrictive sense.

In one aspect, a method of producing a flexible thermoelectric deviceincludes forming a lower conduction layer on top of a lower dielectriclayer, with the lower conduction layer including a plurality ofelectrically conductive pads and a plurality of lower electricallyconductive leads. The plurality of electrically conductive pads includesa plurality of N-designated conductive pads and a plurality ofP-designated conductive pads. Each of the lower electrically conductiveleads connects a pair of neighboring N-designated conductive pad andP-designated conductive pad.

The method includes aligning an N-designated mask on top of the lowerconduction layer. The N-designated mask has a first pattern based on theplurality of N-designated conductive pads of the lower conduction layer.The plurality of N-designated conductive pads of the lower conductionlayer is exposed through the N-designated mask. A plurality of N-typeconduits each on top of one of the N-designated conductive pads exposedthrough the N-designated mask is formed based on the first pattern.

A P-designated mask is aligned on top of the lower conduction layer. TheP-designated mask has a second pattern based on the plurality ofP-designated conductive pads of the lower conduction layer. Theplurality of P-designated conductive pads of the lower conduction layeris exposed through the P-designated mask. A plurality of P-type conduitseach on top of one of the P-designated conductive pads exposed throughthe P-designated mask is formed based on the second pattern.

The method further includes laminating a layer of thermal insulator ontop of and around the plurality of N-type conduits and/or the pluralityof P-type conduits such that the thermal insulator fills a space aroundeach of the N-type conduits and/or P-type conduits, with an internaldielectric layer on top of the layer of thermal insulator. A pluralityof contact holes each through the internal dielectric layer and thelayer of thermal insulator above one of the N-type conduits and/orP-type conduits are drilled.

The method also includes forming an upper conduction layer on top of theinternal dielectric layer and/or through the plurality of contact holes.The upper conduction layer includes a plurality of electricallyconductive contacts and/or a plurality of upper electrically conductiveleads. Each of the electrically conductive contacts is coupled to thetop of one of the N-type conduits and/or P-type conduits through one ofthe contact holes. Each of the upper electrically conductive leadsconnects a pair of neighboring electrically conductive contacts. Anupper dielectric layer is formed on top of the upper conduction layer.

A portion of each of the electrically conductive contacts is locatedbetween the internal dielectric layer and the upper dielectric layer.Each of the N-type conduits and P-type conduits is a thin filmthermoelectric conduit. Each of the N-type conduits contains one or moreN-type thermoelectric material. Each of the P-type conduits contains oneor more P-type thermoelectric material.

Each of the N-type conduits is (1) electrically connected to one of theP-type conduits through an N-designated conductive pad, a lowerelectrically conductive lead, and a P-designated conductive pad in thelower conduction layer, and (2) electrically connected to another one ofthe P-type conduits through two electrically conductive contacts coupledto the top of the two conduits and an upper electrically conductive leadconnecting the two electrically conductive contacts in the upperconduction layer. Similarly, each of the P-type conduits is (1)electrically connected to one of the N-type conduits through aP-designated conductive pad, a lower electrically conductive lead, andan N-designated conductive pad in the lower conduction layer, and (2)electrically connected to another one of the N-type conduits through twoelectrically conductive contacts coupled to the top of the two conduitsand an upper electrically conductive lead connecting the twoelectrically conductive contacts in the upper conduction layer. Theplurality of N-type conduits and P-type conduits are electricallyconnected in series.

Each of the N-type conduits and/or P-type conduits is thermallyinsulated so that a heat energy flows vertically through the thin filmthermoelectric conduit without leaking to other thin film thermoelectricconduits on the sides.

Each dielectric layer may have a thermal conductivity value. Theinternal dielectric layer may be an electrical insulator and/or a poorthermal conductor having the thermal conductivity value less than 1 wattper meter kelvin (W/(mK)). Both the upper dielectric layer and the lowerdielectric layer may be electrical insulators and good thermalconductors having the thermal conductivity value greater than 5 wattsper meter kelvin (W/(mK)).

The thin film thermoelectric conduits may include one or more layer ofthermoelectric material with a combined thickness no greater than 50microns.

A barrier layer may be formed through the N-designated mask, theP-designated mask, and/or a PN-designated mask with one or more of theN-designated conductive pads and/or P-designated conductive padsexposed.

The barrier layer may be between (1) different layers of thermoelectricmaterial within one or more thin film thermoelectric conduit, (2) anelectrically conductive pad and a second thin film thermoelectricconduit, and/or (3) an electrically conductive contact and a third thinfilm thermoelectric conduit. The barrier layer may be electricallyconductive and may have a higher melting temperature than either of thesubstances being separated by the barrier layer.

The forming of the lower conduction layer, the forming of the N-typeconduits, the forming of the P-type conduits, the forming of the upperconduction layer and/or the forming of the upper dielectric layer maycomprise a vacuum deposition, a sputter deposition, a chemical vapordeposition, a physical vapor deposition, an electrochemical deposition,a molecular beam epitaxy, an atomic layer deposition, an electroplating,a screen printing, an etching, a chemical-mechanical planarization, alithography, another deposition method and/or an etching method.

The lower dielectric layer, the internal dielectric layer, and/or theupper dielectric layer may be a flexible polymer, a polymer composite, apolyimide, a polyacrylate, polyvinyl acetate and/or a mylar. Theplurality of electrically conductive pads may be formed from a firstlayer of metal in a first metal clad, a first layer of deposited metal,a first layer of conductive paste, a first electroplated layer, and/or afirst surface plating layer. The plurality of electrically conductivecontacts may be formed from a second layer of metal in a second metalclad, a second layer of deposited metal, a second layer of conductivepaste, a second electroplated layer, and/or a second surface platinglayer.

The lower conduction layer together with the plurality of N-typeconduits and/or the plurality of P-type conduits may be annealed beforethe upper conduction layer is made.

The aligning of the N-designated mask, the forming of the N-typeconduits, the aligning of the P-designated mask, and the forming of theP-type conduits, may all be accomplished within the same vacuum systemwhile continuing to maintain a vacuum.

In another aspect, a method of producing a flexible thermoelectricdevice includes aligning a lower patterned mask on top of a flexiblemetal clad. The lower patterned mask includes a plurality of first areascorresponding to a plurality of electrically conductive pads and aplurality of lower electrically conductive leads. The flexible metalclad includes a layer of metal on top of a lower dielectric layer. Theplurality of electrically conductive pads includes a plurality ofP-designated conductive pads and a plurality of N-designated conductivepads. Each of the lower electrically conductive leads links a pair ofP-designated conductive pad and N-designated conductive pad.

The method includes forming a lower conduction layer of the flexiblethermoelectric device with the lower conduction layer containing theplurality of P-designated conductive pads, the plurality of N-designatedconductive pads and/or the plurality of lower electrically conductiveleads. The lower conduction layer is formed based on the lower patternedmask using the layer of metal of the flexible metal clad by removing ametal outside the plurality of first areas using the lower patternedmask.

A P-designated mask is aligned on top of the lower conduction layer ofthe flexible metal clad. The P-designated mask has a first patterncorresponding to the plurality of P-designated conductive pads of thelower conduction layer. The plurality of P-designated conductive pads isexposed through the P-designated mask.

The method also includes forming a plurality of P-type conduits with oneor more layer of P-type thermoelectric material using the P-designatedmask and one or more kind of the P-type thermoelectric material. Each ofthe P-type conduits is located on top of one of the P-designatedconductive pads of the flexible metal clad exposed through theP-designated mask.

An N-designated mask is aligned on top of the lower conduction layer ofthe flexible metal clad. The N-designated mask has a second patterncorresponding to the plurality of N-designated conductive pads of thelower conduction layer. The plurality of N-designated conductive pads isexposed through the N-designated mask. A plurality of N-type conduits isformed with one or more layer of N-type thermoelectric material usingthe N-designated mask and one or more kind of N-type thermoelectricmaterial. Each of the N-type conduits is located on top of one of theN-designated conductive pads of the flexible metal clad exposed throughthe N-designated mask.

The method further includes drilling a plurality of P-designated contactholes through a flexible coverlay each corresponding to one of theP-type conduits and a plurality of N-designated contact holes throughthe flexible coverlay each corresponding to one of the N-type conduits.The flexible coverlay includes an internal dielectric layer on top of alayer of adhesive. The plurality of P-type conduits and N-type conduitsof the lower conduction layer is aligned under the flexible coverlay.Each of the P-designated contact holes of the flexible coverlay isdirectly above one of the P-type conduits and each of the N-designatedcontact holes of the flexible coverlay is directly above one of theN-type conduits.

The flexible coverlay is laminated on top of the lower conduction layerby pressing the flexible coverlay against the lower conduction layerunder controlled conditions. The layer of adhesive deforms and fills aspace around each of the P-type conduits and/or N-type conduits. Theflexible coverlay is attached to the flexible metal clad through thelayer of adhesive. The flexible coverlay is aligned under an upperpatterned mask. The upper patterned mask has a plurality of second areascorresponding to the plurality of P-designated contact holes andN-designated contact holes, and a plurality of upper electricallyconductive leads.

The method also includes forming an upper conduction layer of theflexible thermoelectric device on top of and through the flexiblecoverlay using the upper patterned mask. The upper conduction layerincludes a plurality of P-designated electrically conductive contactseach in one of the P-designated contact holes coupled to the top of oneof the P-type conduits and a plurality of N-designated electricallyconductive contacts each in one of the N-designated contact holescoupled to the top of one of the N-type conduits. The upper conductionlayer further includes the plurality of upper electrically conductiveleads each connecting a pair of P-designated electrically conductivecontact and N-designated electrically conductive contact.

The method includes sealing and protecting the flexible thermoelectricdevice with an upper dielectric layer. Each of the N-type conduits iselectrically connected to one of the P-type conduits in the lowerconduction layer and to another one of the P-type conduits in the upperconduction layer. Each of the P-type conduits is electrically connectedto one of the N-type conduits in the lower conduction layer and toanother one of the N-type conduits in the upper conduction layer. Theplurality of P-type conduits and N-type conduits are electricallyconnected in series. Each of the P-type conduits and N-type conduits isthermally insulated. A heat energy flows vertically through the conduitwithout leaking to other conduits on the sides.

A PN-designated mask may be aligned above the lower conduction layer ofthe flexible metal clad. The PN-designated mask may have a third patterncorresponding to the plurality of P-designated conductive pads and/orN-designated conductive pads. At least one of the P-designatedconductive pads and/or N-designated conductive pads may be exposedthrough the PN-designated mask.

A soft mask may be used for the lower patterned mask, the P-designatedmask, the N-designated mask and/or the upper patterned mask. A layer ofphoto-resist may be applied to the flexible metal clad, the lowerconduction layer, the plurality of P-type conduits, the plurality ofN-type conduits, the flexible coverlay, and/or the upper conductionlayer of the flexible thermoelectric device. The flexible metal clad ofthe flexible thermoelectric device may be aligned with a photo mask. Thephoto mask may have a fourth pattern corresponding to the lowerpatterned mask, the P-designated mask, the N-designated mask and/or theupper patterned mask. A light from a light source behind the photo maskmay be partially blocked by the photo mask according to the fourthpattern on the photo mask.

The flexible metal clad, the lower conduction layer, the plurality ofP-type conduits, the plurality of N-type conduits, the flexiblecoverlay, and/or the upper conduction layer of the flexiblethermoelectric device, and the layer of photo-resist may be exposed tothe light from the light source through the photo mask.

The method may perform forming a layer of P-type thermoelectricmaterial, N-type thermoelectric material, metal and/or dielectric on theflexible thermoelectric device according to the fourth pattern on thephoto mask. The method may further perform etching the layer of P-typethermoelectric material, N-type thermoelectric material, metal and/ordielectric on the flexible thermoelectric device according to the fourthpattern on the photo mask. Any remaining photo-resist may be removed.

A hard mask may be used for the lower patterned mask, the P-designatedmask, the N-designated mask and/or the upper patterned mask. The lowerpatterned mask, the P-designated mask, the N-designated mask and/or theupper patterned mask may be a stencil. An electroless nickel immersiongold (ENIG) process may be applied to surface plate a layer of nickeland/or a layer of gold over the layer of metal of the flexible metalclad. The method may further include cleaning and rinsing with adeionized water.

In yet another aspect, a method of producing a flexible thermoelectricdevice includes drilling a plurality of P-designated contact holesthrough a flexible coverlay each corresponding to a P-type conduit ontop of a lower conduction layer of the flexible thermoelectric device,and a plurality of N-designated contact holes through the flexiblecoverlay each corresponding to an N-type conduit on top of the lowerconduction layer.

The flexible coverlay includes a layer of adhesive under an internaldielectric layer. The plurality of P-type conduits and N-type conduitsis aligned under the flexible coverlay. Each of the P-designated contactholes of the flexible coverlay is directly above one of the P-typeconduits and each of the N-designated contact holes of the flexiblecoverlay is directly above one of the N-type conduits.

Each of the P-type conduits is electrically connected to one of theN-type conduits through a P-designated conductive pad and anN-designated conductive pad connected by a lower electrically conductivelead in the lower conduction layer above a lower dielectric layer of theflexible thermoelectric device.

The flexible coverlay is laminated on top of the lower conduction layerby pressing the flexible coverlay against the lower conduction layerunder controlled conditions. The layer of adhesive deforms and fills aspace around each of the P-type conduits and/or N-type conduits. Theflexible coverlay is attached to the lower conduction layer through thelayer of adhesive.

The method further includes aligning the flexible coverlay under anupper patterned screen. The upper patterned screen includes a pluralityof first areas corresponding to the plurality of P-designated contactholes and N-designated contact holes, and a plurality of second areascorresponding to a plurality of upper electrically conductive leads. Themethod also includes screen printing an upper conduction layer of theflexible thermoelectric device on top of and through the flexiblecoverlay by pressing a conductive paste through the upper patternedscreen.

The conductive paste penetrates each P-designated contact hole to forman electrically conductive contact coupled to the top of one of theP-type conduits. The conductive paste penetrates each N-designatedcontact hole to form another electrically conductive contact coupled tothe top of one of the N-type conduits. The conductive paste at each ofthe second areas forms an upper electrically conductive lead connectinga pair of electrically conductive contacts.

The method includes sealing and protecting the flexible thermoelectricdevice with an upper dielectric layer. The plurality of P-type conduitsand N-type conduits are electrically connected in series. Each of theP-type conduits and N-type conduits is thermally insulated. A heatenergy flows vertically through the conduit without leaking to otherconduits on the sides.

The methods and device disclosed herein may be implemented in any meansfor achieving various aspects. Other features will be apparent from theaccompanying drawings and from the detailed description that follows.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments of this invention are illustrated by way of example andnot limitation in the Figures of the accompanying drawings, in whichlike references indicate similar elements and in which:

FIG. 1 is an exploded view of a flexible thermoelectric deviceillustrating an active layer of thin film thermoelectric conduitsbetween a lower conduction layer and an upper conduction layerinterleaved with a lower dielectric layer, an internal dielectric layerand an upper dielectric layer, according to one embodiment.

FIG. 2 shows a cross-sectional view of the flexible thermoelectricdevice of FIG. 1, comprising N-type conduits made of N-typethermoelectric material(s) and P-type conduits made of P-typethermoelectric material(s), according to one embodiment.

FIG. 3 illustrates a conduit view of the flexible thermoelectric deviceof FIG. 1, comprising a P-type conduit with more than one layer ofthermoelectric material separated by barrier layers, according to oneembodiment.

FIG. 4 illustrates a lower patterned mask view of the flexiblethermoelectric device of FIG. 1, showing a lower patterned mask alignedon top of a metal clad in preparation for forming a lower conductionlayer with electrically conductive pads and lower electricallyconductive leads, according to one embodiment.

FIG. 5 is a P-designated mask view of the flexible thermoelectric deviceof FIG. 1, illustrating a P-designated mask aligned on top of the lowerconduction layer in preparation for forming P-type conduits on top ofP-designated conductive pads, according to one embodiment.

FIG. 6 is an N-designated mask view of the flexible thermoelectricdevice of FIG. 1, illustrating an N-designated mask aligned on top ofthe lower conduction layer in preparation for forming N-type conduits ontop of N-designated conductive pads, according to one embodiment.

FIG. 7 is a PN-designated mask view of the flexible thermoelectricdevice of FIG. 1, illustrating a PN-designated mask aligned on top ofthe lower conduction layer in preparation for forming a barrier layer onP-type conduits and N-type conduits, according to one embodiment.

FIG. 8 is a flexible coverlay view of the flexible thermoelectric deviceof FIG. 1, illustrating a flexible coverlay with drilled contact holesaligned on top of P-type conduits and N-type conduits in preparation forlamination, according to one embodiment.

FIG. 9 is an upper patterned mask view of the flexible thermoelectricdevice of FIG. 1, illustrating an upper patterned mask aligned on top ofthe contact holes in the flexible coverlay in preparation for forming anupper conduction layer on top of and through the flexible coverlay usingthe upper patterned mask, according to one embodiment.

FIG. 10 is an upper dielectric layer view of the flexible thermoelectricdevice of FIG. 1, illustrating an upper dielectric layer formed on topof the upper conduction layer and the internal dielectric layer,according to one embodiment.

FIG. 11 illustrates the finished view of the flexible thermoelectricdevice of FIG. 1, according to one embodiment.

FIG. 12 illustrates the cut away view of the flexible thermoelectricdevice of FIG. 1 with the dielectrics and thermal insulators removed,illustrating the thermoelectric conduits electrically connected inseries via the upper conduction layer and lower conduction layer,according to one embodiment.

FIG. 13 is an electrical conduction path view of the flexiblethermoelectric device of FIG. 1, illustrating the electrical conductionpath through the series of interconnecting P-type conduits and N-typeconduits of the flexible thermoelectric device, according to oneembodiment.

FIG. 14 is a thermal conduction path view of the flexible thermoelectricdevice of FIG. 1, illustrating a plurality of thermal conduction pathseach going through one of the P-type conduits and N-type conduits of theflexible thermoelectric device, according to one embodiment.

FIG. 15A shows a process flow to produce a flexible thermoelectricdevice of FIG. 1, according to one embodiment.

FIG. 15B is continuation of the process flow of FIG. 15A, according toone embodiment.

FIG. 16A illustrates another process flow to produce a flexiblethermoelectric device of FIG. 1, according to one embodiment.

FIG. 16B is continuation of the process flow of FIG. 16A, according toone embodiment.

FIG. 16C is continuation of the process flow of FIG. 16B, according toone embodiment.

FIG. 17 illustrates yet another process flow to produce a flexiblethermoelectric device, according to one embodiment.

FIG. 18 is a wearable device view of the flexible thermoelectric deviceof FIG. 1, illustrating two examples of the flexible thermoelectricdevice harvesting energy for wearable applications, according to oneembodiment.

Other features of the present embodiments will be apparent from theaccompanying drawings and from the detailed description that follows.

DETAILED DESCRIPTION

Example embodiments, as described below, may be used to provide a methodof producing a flexible thermoelectric device to harvest energy forwearable applications. Although the present embodiments have beendescribed with reference to specific example embodiments, it will beevident that various modifications and changes may be made to theseembodiments without departing from the broader spirit and scope of thevarious embodiments.

In one embodiment, a method of producing a flexible thermoelectricdevice 100 includes forming a lower conduction layer 104 on top of alower dielectric layer 102, with the lower conduction layer 104including a plurality of electrically conductive pads 107 and aplurality of lower electrically conductive leads 110. The plurality ofelectrically conductive pads 107 includes a plurality of N-designatedconductive pads 106 and a plurality of P-designated conductive pads 108.Each of the lower electrically conductive leads 110 connects a pair ofneighboring N-designated conductive pad 106 and P-designated conductivepad 108.

The method includes aligning an N-designated mask 600 on top of thelower conduction layer 104. The N-designated mask 600 has a firstpattern based on the plurality of N-designated conductive pads 106 ofthe lower conduction layer 104. The plurality of N-designated conductivepads 106 of the lower conduction layer 104 is exposed through theN-designated mask 600. A plurality of N-type conduits 112 each on top ofone of the N-designated conductive pads 106 exposed through theN-designated mask 600 is formed based on the first pattern.

A P-designated mask 500 is aligned on top of the lower conduction layer104. The P-designated mask 500 has a second pattern based on theplurality of P-designated conductive pads 108 of the lower conductionlayer 104. The plurality of P-designated conductive pads 108 of thelower conduction layer 104 is exposed through the P-designated mask 500.A plurality of P-type conduits 114 each on top of one of theP-designated conductive pads 108 exposed through the P-designated mask500 is formed based on the second pattern.

The method further includes laminating a layer of thermal insulator 120on top of and around the plurality of N-type conduits 112 and/or theP-type conduits 114 such that the thermal insulator 120 fills a spacearound each of the N-type conduits 112 and/or P-type conduits 114, withan internal dielectric layer 118 on top of the layer of thermalinsulator 120. A plurality of contact holes 122 each through theinternal dielectric layer 118 and the layer of thermal insulator 120above one of the N-type conduits 112 and/or P-type conduits 114 aredrilled.

The method also includes forming an upper conduction layer 124 on top ofthe internal dielectric layer 118 and/or through the plurality ofcontact holes 122. The upper conduction layer 124 includes a pluralityof electrically conductive contacts 126 and/or a plurality of upperelectrically conductive leads 128. Each of the electrically conductivecontacts 126 is coupled to the top of one of the N-type conduits 112 andP-type conduits 114 through one of the contact holes 122. Each of theupper electrically conductive leads 128 connects a pair of neighboringelectrically conductive contacts 126. An upper dielectric layer 130 isformed on top of the upper conduction layer 124.

A portion of each of the electrically conductive contacts 126 is locatedbetween the internal dielectric layer 118 and the upper dielectric layer130. Each of the N-type conduits 112 and P-type conduits 114 is a thinfilm thermoelectric conduit 113. Each of the N-type conduits 112contains one or more N-type thermoelectric material 200. Each of theP-type conduits 114 contains one or more P-type thermoelectric material202.

Each of the N-type conduits 112 is (1) electrically connected to one ofthe P-type conduits 114 through an N-designated conductive pad 106, alower electrically conductive lead 110, and a P-designated conductivepad 108 in the lower conduction layer 104, and (2) electricallyconnected to another one of the P-type conduits 114 through twoelectrically conductive contacts 126 coupled to the top of the twoconduits and an upper electrically conductive lead 128 connecting thetwo electrically conductive contacts 126 in the upper conduction layer124. Similarly, each of the P-type conduits 114 is (1) electricallyconnected to one of the N-type conduits 112 through a P-designatedconductive pad 108, a lower electrically conductive lead 110, and anN-designated conductive pad 106 in the lower conduction layer 104, and(2) electrically connected to another one of the N-type conduits 112through two electrically conductive contacts 126 coupled to the top ofthe two conduits (e.g., N-type conduits 112, P-type conduits 114) and anupper electrically conductive lead 128 connecting the two electricallyconductively contacts 126 in the upper conduction layer 124. Theplurality of N-type conduits 112 and P-type conduits 114 areelectrically connected in series.

Each of the N-type conduits 112 and/or P-type conduits 114 is thermallyinsulated so that a heat energy flows vertically through the thin filmthermoelectric conduit 113 without leaking to other thin filmthermoelectric conduits 113 on the sides.

Each dielectric layer may have a thermal conductivity value. Theinternal dielectric layer 118 may be an electrical insulator and/or apoor thermal conductor having the thermal conductivity value less than 1watt per meter kelvin (W/(mK)). Both the upper dielectric layer 130 andthe lower dielectric layer 102 may be electrical insulators and/or goodthermal conductors having the thermal conductivity value greater than 5watts per meter kelvin (W/(mK)).

The thin film thermoelectric conduits 113 may include one or more layerof thermoelectric material with a combined thickness no greater than 50microns.

A barrier layer 300A-300C may be formed through the N-designated mask600, the P-designated mask 500, and/or a PN-designated mask 700 with oneor more of the N-designated conductive pads 106 and/or P-designatedconductive pads 108 exposed.

The barrier layer 300A-300C may be between (1) different layers ofthermoelectric material (e.g. 200 and/or 202) within one or more thinfilm thermoelectric conduit 113, (2) an electrically conductive pad 107and a second thin film thermoelectric conduit 113, and/or (3) anelectrically conductive contact 126 and a third thin film thermoelectricconduit 113. The barrier layer 300A-300C may be electrically conductiveand may have a higher melting temperature than either of the substancesbeing separated by the barrier layer 300A-300C.

The forming of the lower conduction layer 104, the forming of the N-typeconduits 112, the forming of the P-type conduits 114, the forming of theupper conduction layer 124 and/or the forming of the upper dielectriclayer 130 may comprise a vacuum deposition, a sputter deposition, achemical vapor deposition, a physical vapor deposition, anelectrochemical deposition, a molecular beam epitaxy, an atomic layerdeposition, an electroplating, a screen printing, an etching, achemical-mechanical planarization, a lithography, another depositionmethod and/or an etching method.

The lower dielectric layer 102, the internal dielectric layer 118,and/or the upper dielectric layer 130 may be a flexible polymer, apolymer composite, a polyimide, a polyacrylate, a polyvinyl acetateand/or a mylar. The plurality of electrically conductive pads 107 may beformed from a first layer of metal 402 in a first metal clad 103, afirst layer of deposited metal, a first layer of conductive paste (e.g.,conductive paste 304), a first electroplated layer, and/or a firstsurface plating layer 302. The plurality of electrically conductivecontacts 126 may be formed from a second layer of metal 402 in a secondmetal clad 103, a second layer of deposited metal, a second layer ofconductive paste (e.g., conductive paste 304), a second electroplatedlayer, and/or a second surface plating layer 302.

The lower conduction layer 104 together with the plurality of N-typeconduits 112 and/or the plurality of P-type conduits 114 may be annealedbefore the upper conduction layer 124 is made.

The aligning of the N-designated mask 600, the forming of the N-typeconduits 112, the aligning of the P-designated mask 500, and the formingof the P-type conduits 114, may all be accomplished within the samevacuum system while continuing to maintain a vacuum.

In another embodiment, a method of producing a flexible thermoelectricdevice 100 includes aligning a lower patterned mask 400 on top of aflexible metal clad 103. The lower patterned mask 400 includes aplurality of first areas corresponding to a plurality of electricallyconductive pads 107 and a plurality of lower electrically conductiveleads 110. The flexible metal clad 103 includes a layer of metal 402 ontop of a lower dielectric layer 102. The plurality of electricallyconductive pads 107 includes a plurality of P-designated conductive pads108 and a plurality of N-designated conductive pads 106. Each of thelower electrically conductive leads 110 links a pair of P-designatedconductive pad 108 and N-designated conductive pad 106.

The method includes forming a lower conduction layer 104 of the flexiblethermoelectric device 100 with the lower conduction layer containing theplurality of P-designated conductive pads 108, the plurality ofN-designated conductive pads 106 and/or the plurality of lowerelectrically conductive leads 110. The lower conduction layer 104 isformed based on the lower patterned mask 400 using the layer of metal402 of the flexible metal clad 103 by removing a metal outside theplurality of first areas using the lower patterned mask 400.

A P-designated mask 500 is aligned on top of the lower conduction layer104 of the flexible metal clad 103. The P-designated mask 500 has afirst pattern corresponding to the plurality of P-designated conductivepads 108 of the lower conduction layer 104. The plurality ofP-designated conductive pads 108 is exposed through the P-designatedmask 500.

The method also includes forming a plurality of P-type conduits 114 withone or more layer of P-type thermoelectric material 202 using theP-designated mask 500 and one or more kind of the P-type thermoelectricmaterial 202. Each of the P-type conduits 114 is located on top of oneof the P-designated conductive pads 108 of the flexible metal clad 103exposed through the P-designated mask 500.

An N-designated mask 600 is aligned on top of the lower conduction layer104 of the flexible metal clad 103. The N-designated mask 600 has asecond pattern corresponding to the plurality of N-designated conductivepads 106 of the lower conduction layer 104. The plurality ofN-designated conductive pads 106 is exposed through the N-designatedmask 600. A plurality of N-type conduits 112 is formed with one or morelayer of N-type thermoelectric material 200 using the N-designated mask600 and one or more kind of N-type thermoelectric material 200. Each ofthe N-type conduits 112 is located on top of one of the N-designatedconductive pads 106 of the flexible metal clad 103 exposed through theN-designated mask 600.

The method further includes drilling a plurality of P-designated contactholes (e.g., contact holes 122) through a flexible coverlay 119 eachcorresponding to one of the P-type conduits 114 and a plurality ofN-designated contact holes (e.g., contact holes 122) through theflexible coverlay 119 each corresponding to one of the N-type conduits112. The flexible coverlay 119 includes an internal dielectric layer 118on top of a layer of adhesive (e.g., thermal insulator (adhesive) 120).The plurality of P-type conduits 114 and N-type conduits 112 of thelower conduction layer 104 is aligned under the flexible coverlay 119.Each of the P-designated contact holes (e.g., contact holes 122) of theflexible coverlay 119 is directly above one of the P-type conduits 114and each of the N-designated contact holes (e.g., contact holes 122) ofthe flexible coverlay 119 is directly above one of the N-type conduits112.

The flexible coverlay 119 is laminated on top of the lower conductionlayer 104 by pressing the flexible coverlay 119 against the lowerconduction layer 104 under controlled conditions. The layer of adhesive(e.g., thermal insulator (adhesive) 120) deforms and fills a spacearound each of the P-type conduits 114 and/or N-type conduits 112. Theflexible coverlay 119 is attached to the flexible metal clad 103 throughthe layer of adhesive (e.g., thermal insulator (adhesive) 120). Theflexible coverlay 119 is aligned under an upper patterned mask 900. Theupper patterned mask 900 has a plurality of second areas correspondingto the plurality of P-designated contact holes (e.g., contact holes 122)and N-designated contact holes (e.g., contact holes 122), and aplurality of upper electrically conductive leads 128.

The method also includes forming an upper conduction layer 124 of theflexible thermoelectric device 100 on top of and through the flexiblecoverlay 119 using the upper patterned mask 900. The upper conductionlayer 124 includes a plurality of P-designated electrically conductivecontacts (e.g., electrically conductive contacts 126) each in one of theP-designated contact holes (e.g., contact holes 122) coupled to the topof one of the P-type conduits 114 and a plurality of N-designatedelectrically conductive contacts (e.g., electrically conductive contacts126) each in one of the N-designated contact holes (e.g., contact holes122) coupled to the top of one of the N-type conduits 112. The upperconduction layer 124 further includes the plurality of upperelectrically conductive leads 128 each connecting a pair of P-designatedelectrically conductive contact (e.g., electrically conductive contacts126) and N-designated electrically conductive contact (e.g.,electrically conductive contacts 126).

The method includes sealing and protecting the flexible thermoelectricdevice 100 with an upper dielectric layer 130. Each of the N-typeconduits 112 is electrically connected to one of the P-type conduits 114in the lower conduction layer 104 and to another one of the P-typeconduits 114 in the upper conduction layer 124. Each of the P-typeconduits 114 is electrically connected to one of the N-type conduits 112in the lower conduction layer 104 and to another one of the N-typeconduits 112 in the upper conduction layer 124. The plurality of P-typeconduits 114 and N-type conduits 112 are electrically connected inseries. Each of the P-type conduits 114 and N-type conduits 112 isthermally insulated. A heat energy flows vertically through the conduitwithout leaking to other conduits on the sides.

A PN-designated mask 700 may be aligned above the lower conduction layer104 of the flexible metal clad 103. The PN-designated mask 700 may havea third pattern corresponding to the plurality of P-designatedconductive pads 108 and/or N-designated conductive pads 106. At leastone of the P-designated conductive pads 108 and/or N-designatedconductive pads 106 may be exposed through the PN-designated mask 700.

A soft mask may be used for the lower patterned mask 400, theP-designated mask 500, the N-designated mask 600 and/or the upperpatterned mask 900. A layer of photo-resist may be applied to theflexible metal clad 103, the lower conduction layer 104, the pluralityof P-type conduits 114, the plurality of N-type conduits 112, theflexible coverlay 119, and/or the upper conduction layer 124 of theflexible thermoelectric device 100. The flexible metal clad 103 of theflexible thermoelectric device 100 may be aligned with a photo mask. Thephoto mask may have a fourth pattern corresponding to the lowerpatterned mask 400, the P-designated mask 500, the N-designated mask 600and/or the upper patterned mask 900. A light from a light source behindthe photo mask may be partially blocked by the photo mask according tothe fourth pattern on the photo mask.

The flexible metal clad 103, the lower conduction layer 104, theplurality of P-type conduits 114, the plurality of N-type conduits 112,the flexible coverlay 119, and/or the upper conduction layer 124 of theflexible thermoelectric device 100, and the layer of photo-resist may beexposed to the light from the light source through the photo mask.

The method may perform forming a layer of P-type thermoelectric material202, N-type thermoelectric material 200, metal and/or dielectric on theflexible thermoelectric device 100 according to the fourth pattern onthe photo mask. The method may further perform etching the layer ofP-type thermoelectric material 202, N-type thermoelectric material 200,metal and/or dielectric on the flexible thermoelectric device 100according to the fourth pattern on the photo mask. Any remainingphoto-resist may be removed.

A hard mask may be used for the lower patterned mask 400, theP-designated mask 500, the N-designated mask 600 and/or the upperpatterned mask 900. The lower patterned mask 400, the P-designated mask500, the N-designated mask 600 and/or the upper patterned mask 900 maybe a stencil. An electroless nickel immersion gold (ENIG) process may beapplied to surface plate a layer of nickel and/or a layer of gold overthe layer of metal 402 of the flexible metal clad 103. The method mayfurther include cleaning and rinsing with a deionized water.

In yet another embodiment, a method of producing a flexiblethermoelectric device 100 includes drilling a plurality of P-designatedcontact holes (e.g., contact holes 122) through a flexible coverlay 119each corresponding to a P-type conduit 114 on top of a lower conductionlayer 104 of the flexible thermoelectric device 100, and a plurality ofN-designated contact holes (e.g., contact holes 122) through theflexible coverlay 119 each corresponding to an N-type conduit 112 on topof the lower conduction layer 104.

The flexible coverlay 119 includes a layer of adhesive (e.g., thermalinsulator (adhesive) 120) under an internal dielectric layer 118. Theplurality of P-type conduits 114 and N-type conduits 112 is alignedunder the flexible coverlay 119. Each of the P-designated contact holes(e.g., contact holes 122) of the flexible coverlay 119 is directly aboveone of the P-type conduits 114 and each of the N-designated contactholes (e.g., contact holes 122) of the flexible coverlay 119 is directlyabove one of the N-type conduits 112.

Each of the P-type conduits 114 is electrically connected to one of theN-type conduits 112 through a P-designated conductive pad 108 and anN-designated conductive pad 106 connected by a lower electricallyconductive lead 110 in the lower conduction layer 104 above a lowerdielectric layer 102 of the flexible thermoelectric device 100.

The flexible coverlay 119 is laminated on top of the lower conductionlayer 104 by pressing the flexible coverlay 119 against the lowerconduction layer 104 under controlled conditions. The layer of adhesive(e.g., thermal insulator (adhesive) 120) deforms and fills a spacearound each of the P-type conduits 114 and/or N-type conduits 112. Theflexible coverlay 119 is attached to the lower conduction layer 104through the layer of adhesive (e.g., thermal insulator (adhesive) 120).

The method further includes aligning the flexible coverlay 119 under anupper patterned screen (e.g., upper patterned mask 900). The upperpatterned screen (e.g., upper patterned mask 900) includes a pluralityof first areas corresponding to the plurality of P-designated contactholes (e.g., contact holes 122) and N-designated contact holes (e.g.,contact holes 122), and a plurality of second areas corresponding to aplurality of upper electrically conductive leads 128. The method alsoincludes screen printing an upper conduction layer 124 of the flexiblethermoelectric device 100 on top of and through the flexible coverlay119 by pressing a conductive paste 304 through the upper patternedscreen (e.g., upper patterned mask 900).

The conductive paste 304 penetrates each P-designated contact hole (e.g.contact hole 122) to form an electrically conductive contact 126 coupledto the top of one of the P-type conduits 114. The conductive paste 304penetrates each N-designated contact hole (e.g. contact hole 122) toform another electrically conductive contact 126 coupled to the top ofone of the N-type conduits 112. The conductive paste 304 at each of thesecond areas forms an upper electrically conductive lead 128 connectinga pair of electrically conductive contacts 126.

The method includes sealing and protecting the flexible thermoelectricdevice 100 with an upper dielectric layer 130. The plurality of P-typeconduits 114 and N-type conduits 112 are electrically connected inseries. Each of the P-type conduits 114 and N-type conduits 112 isthermally insulated. A heat energy flows vertically through the conduitwithout leaking to other conduits on the sides.

FIG. 1 is an exploded view 150 of a flexible thermoelectric device 100illustrating an active layer 116 of thin film thermoelectric conduits113 between a lower conduction layer 104 and an upper conduction layer124 interleaved with a lower dielectric layer 102, an internaldielectric layer 118 and an upper dielectric layer 130, according to oneembodiment.

In one embodiment, a system of the flexible thermoelectric device 100with conductive parts of flexible thermoelectric device 101 may includea lower dielectric layer 102, a lower conduction layer 104 with a lowerelectrically conductive lead 110 and an electrically conductive pad 107which may be an N-designated conductive pad 106 or a P-designatedconductive pad 108, an active layer 116 with a thin film thermoelectricconduit 113 which may be a P-type conduits 114 or an N-type conduit 112,a flexible coverlay 119 with an internal dielectric layer 118 and athermal insulator (adhesive) 120 and a contact hole 122 drilled throughthe flexible coverlay 119, and an upper conduction layer 124 with anelectrically conductive contact 126, an upper electrically conductivelead 128, and an upper dielectric layer 130, according to oneembodiment.

The flexible thermoelectric device 100 may be a flexible device whichconverts heat (i.e. a temperature differential) directly into electricalenergy. Furthermore, applying a current to a thermoelectric device maycreate a temperature differential, which may be used to heat and/or coola surface.

The conductive parts of flexible thermoelectric device 101 may includethe upper conduction layer 124, the active layer 116, and the lowerconduction layer 104 with the N-type conduits 112 and P-type conduits114 connected in series. The conductive parts of flexible thermoelectricdevice 101 functions as an electrical conduction path 1300 such that anelectrical energy flows in a zig-zag manner through the conductive partsof flexible thermoelectric device 101. Overall, the electrical energyflows in a “horizontal” manner.

The lower dielectric layer 102 may be a flexible dielectric materialwhich provides structure to the flexible thermoelectric device 100. Inan example embodiment, the lower dielectric layer 102 may be bothelectrical insulator and good thermal conductor having a thermalconductivity value greater than 5 watts per meter kelvin (W/(mK)).

In various embodiments, the lower dielectric layer 102 may be a flexiblepolymer material which has a high thermal conductivity, and is alsoelectrically insulating. Examples of flexible polymer material mayinclude, but are not limited to, polyimide which has been doped toincrease thermal conductivity. In some embodiments, the lower dielectriclayer 102 may be between 1 millimeter and 10 millimeters thick. Thelower dielectric layer 102 may also be metal-clad, such as copper-cladKapton tape. The lower dielectric layer 102 should be chosen such thatit will not melt at the temperatures associated with the production ofthe flexible thermoelectric device 100 (e.g. the high temperaturesassociated with sputter deposition, etc.).

The metal clad 103 may be a composite of two or more dissimilar metals,metallurgically bonded together, to achieve improved functionalcharacteristics. The metal clad 103 may also be a layer of metal 402 ontop of a layer of dielectric. The layer of metal 402 and the layer ofdielectric (e.g., lower dielectric layer 102) may be bonded together.

The plurality of electrically conductive pads 107 may be formed from alayer of metal 402 in a metal clad 103. The process of metal claddingmay include metallic electroplating applied to a polymer sheet. Examplesinclude of metal clad 103 may include, but are not limited to,copper-clad Kapton tape. In some embodiments, the metal cladding may beremoved from the polymer sheet using resist and an etchant.

The lower conduction layer 104 may include the plurality of electricallyconductive pads 107 and a plurality of lower electrically conductiveleads 110. A pair of neighboring N-type conduit 112 and P-type conduit114 may be electrically connected via an N-designated conductive pad 106and a P-designated conductive pad 108 connected by a lower electricallyconductive lead 110 in the lower conduction layer 104.

The N-designated conductive pad 106 may be a conductive pad in the lowerconduction layer 104 to connect an N-type conduit 112 in series with aneighboring P-type conduit 114 through a lower electrically conductivelead 110 and a P-designated conductive pad 108.

The electrically conductive pad 107 may be a flat area which may beaffixed to a material or component, or to which a material or componentmay be affixed to make an electrical connection. The plurality ofelectrically conductive pad 107 may include a plurality of N-designatedconductive pads 106 and a plurality of P-designated conductive pads 108.

The P-designated conductive pad 108 may be a conductive pad in the lowerconduction layer 104 to connect a P-type conduit 114 in series with aneighboring N-type conduit 112 through a lower electrically conductivelead 110 and an N-designated conductive pad 106.

In some embodiments, these two types (e.g., P-designated andN-designated) of pads may possess identical materials and properties.They may differ in appearance to aid in device construction and testing.For example, in one embodiment, the N-designated conductive pads 106 andP-designated conductive pads 108 may simply be given different shapes toindicate the material type designation.

In other embodiments, however, these two pad types may differ in moresubstantial ways. For example, in one embodiment, the N-designatedconductive pads 106 and P-designated conductive pads 108 may be composedof different conductive materials which are optimized for the N-typeconduits 112 and P-type conduits 114 to be formed upon them (e.g. have asimilar crystal structure, etc.). In such an embodiment, theN-designated conductive pads 106 and the P-designated conductive pads108 may be created using N-designated masks 600 and P-designated masks500, and may be affixed to interconnected conductive pads (e.g.,N-designated conductive pads 106, P-designated conductive pads 108).

The lower electrically conductive lead 110 may be a conducting materialwhich connects two points of a circuit together in the lower conductionlayer 104. In one embodiment, the lower electrically conductive lead 110may be a conducting material (e.g. etched cladding, vacuum deposition,surface plating, electroplating, etc.) applied directly to the surfaceof the lower conduction layer 104. In another embodiment, the lowerelectrically conductive lead 110 may be a wire. The lower electricallyconductive lead 110 may connect a pair of neighboring N-designatedconductive pad 106 and P-designated conductive pad 108.

The N-type conduits 112 may be a layer and/or a stack of layers ofmaterials within the flexible thermoelectric device 100. The materialsmay include, at least in part, one or more N-type thermoelectricmaterial(s) 200 in which the primary charge carrier is electrons.According to various embodiments, an N-type conduit 112 may include thinfilm N-type thermoelectric materials 200, conductive materials, barrierlayers (300A, 300B, 300C), and/or conductive adhesive layers (e.g.,conductive paste 304).

The thin film thermoelectric conduit 113 may be a layer ofthermoelectric material and/or a stack of layered materials whichcomprise thermoelectric materials. In one embodiment, some or all ofthese layers may be formed or deposited as a thin film, whose thicknessmay range from sub-nanometer to micrometers.

The lower conduction layer 104 and the upper conduction layer 124 may belayers within the flexible thermoelectric device 100 which are comprisedof electrically conductive material electrically coupled to the thinfilm thermoelectric conduits 113. In various embodiments, the thin filmthermoelectric conduit 113 may be incorporated into the flexiblethermoelectric device 100 in such a way that it serves as a conduit forheat from one side of the device to the other.

In an example embodiment, each of the N-type conduits 112 may be a thinfilm thermoelectric conduit 113 that includes an N-type thermoelectricmaterial 200. In another example embodiment, each of the P-type conduits114 may be a thin film thermoelectric conduit 113 that includes a P-typethermoelectric material 202.

The P-type conduits 114 may be a layer or a stack of layers of materialswithin the flexible thermoelectric device 100 which is comprised, atleast in part, of one or more P-type thermoelectric materials 202 inwhich the primary charge carrier is positive holes. According to variousembodiments, a P-type conduit 114 may comprise thin film P-typethermoelectric materials 202, conductive materials, barrier layers(300A, 300B, 300C), and/or conductive adhesive layers.

The active layer 116 may be a portion of the flexible thermoelectricdevice 100 which comprises thermoelectric materials (e.g., P-typethermoelectric materials 202, N-type thermoelectric material 200). Insome embodiments, the active layer 116 may further comprise materialsand/or components which are not thermoelectric or electricallyconductive. The active layer 116 may be the surface and/or coating ofthin film thermoelectric conduit 113 between a lower conduction layer104 and an upper conduction layer 124 of the flexible thermoelectricdevice 100.

The internal dielectric layer 118 may be a flexible dielectric materialwhich has poor thermal conductivity and is also electrically insulating.Examples include, but are not limited to Teflon. The internal dielectriclayer 118 may be an electrical insulator and a poor thermal conductorhaving a thermal conductivity value less than 1 watts per meter kelvin(W/(mK)).

The flexible coverlay 119 may be a material laminated to the outsidelayers of the circuit to insulate the copper conductor. The flexiblecoverlay 119 may include an internal dielectric layer 118 on top of alayer of adhesive (e.g., thermal insulator (adhesive) 120). The flexiblecoverlay 119 serves as a solder resist for flexible printed circuitboards. Conventional solder masks have only a limited bendability, sofor flex-circuits that require greater bendability, the flexiblecoverlay 119 may be glued on to protect the copper structure. Theflexible coverlay 119 may have a layer of glue and a layer of dielectric(Adhesive+dielectric).

The thermal insulator (adhesive) 120 may be a material which reduces theconduction of thermal energy. In the context of the present description,the thermal insulator (adhesive) 120 may also be electricallyinsulating. The thermal insulator (adhesive) 120 may be a cross-linkedpolymer adhesive, such as prepeg or other resins with similarproperties.

The contact hole 122 may be a passage created through material whichseparates the upper electrically conductive leads 128 of the upperconduction layer 124 and the thin film thermoelectric conduits 113 ofthe active layer 116. Specifically, the contact hole 122 may be apassage through the thermal insulator (adhesive) 120 and/or the internaldielectric layer 118 which are on top of a thin film thermoelectricconduit 113. In various embodiments, the contact hole 122 may be formedby drilling through the material above a thin film thermoelectricconduit 113, either mechanically or using a laser.

The upper conduction layer 124 may be a layer within the flexiblethermoelectric device 100 comprised of electrically conductive materialelectrically coupled to the thin film thermoelectric conduits 113. Theupper conduction layer 124 may be formed on top of the internaldielectric layer 118 and through the plurality of contact holes 122including a plurality of electrically conductive contacts 126 and aplurality of upper electrically conductive leads 128. Each of theelectrically conductive contacts 126 may be coupled to the top of one ofthe N-type conduits 112 and P-type conduits 114 through one of thecontact holes 122. Each of the upper electrically conductive leads 128may connect a pair of neighboring electrically conductive contacts 126.

The electrically conductive contact 126 may be a conductive element inelectrical contact with a material and/or a component. In someembodiments, the electrically conductive contact 126 may resemble a pin.In other embodiments, the electrically conductive contact 126 may beflat, like an electrically conductive pad 107.

The upper electrically conductive lead 128 may be a conducting materialwhich connects two points of a circuit together in the upper conductionlayer 124. In one embodiment, the upper electrically conductive lead 128may be a conducting material (e.g. etched cladding, vacuum deposition,surface plating, electroplating, etc.) applied directly to the surfaceof the internal dielectric layer 118. In another embodiment, the lowerelectrically conductive lead 110 may be a wire. The upper electricallyconductive lead 128 may each connect a pair of neighboring electricallyconductive contacts 126 in the upper conduction layer 124.

The upper dielectric layer 130 may be formed on the top of the upperconduction layer 124. The upper dielectric layer 130 may be electricalinsulator and good thermal conductor having a thermal conductivity valuegreater than 5 watts per meter kelvin (W/(mK)).

FIG. 2 illustrates a cross-sectional view 250 of the flexiblethermoelectric device 100 of FIG. 1, comprising N-type conduits 112 madeof N-type thermoelectric material(s) 200 and P-type conduits 114 made ofP-type thermoelectric material(s) 202, according to one embodiment.Particularly, FIG. 2 builds on FIG. 1, and further adds an N-typethermoelectric material 200 and a P-type thermoelectric material 202.

The N-type thermoelectric material 200 may be a thermoelectric materialin which the primary charge carrier is electrons. Plurality of N-typeconduits 112 may be formed with one or more layer of N-typethermoelectric material 200 using the N-designated mask 600 and one ormore kind of N-type thermoelectric material 200.

The P-type thermoelectric material 202 may be a thermoelectric materialin which the primary charge carrier is positive holes. Plurality ofP-type conduits 114 may be formed with one or more layer of P-typethermoelectric material 202 using the P-designated mask 500 and one ormore kind of P-type thermoelectric material 202.

Each N-type conduit 112 is electrically connected to one neighboringP-type conduit 114 in the lower conduction layer 104 and is electricallyconnected to another neighboring P-type conduit 114 in the upperconduction layer 124. Similarly, each P-type conduit 114 is electricallyconnected to one neighboring N-type conduit 112 in the lower conductionlayer 104 and is electrically connected to another neighboring N-typeconduit 112 in the upper conduction layer 124 such that the N-typeconduits 112 and P-type conduits 114 are effectively connected inseries.

FIG. 3 illustrates a conduit view 350 of the flexible thermoelectricdevice 100 of FIG. 1, comprising a P-type conduit 114 with more than onelayer of thermoelectric material separated by barrier layers 300A, 300B,and 300C, according to one embodiment. Particularly, FIG. 3 builds onFIG. 1, and further adds a barrier layer 300A, 300B and 300C, a surfaceplating layer 302 and a conductive paste 304.

The barrier layers 300A, 300B, 300C may be a layer of material thatprevents the corruption (e.g. diffusion, sublimation, etc.) of one layerby another, according to one embodiment. It may also be known as adiffusion barrier. In many embodiments, a diffusion barrier may be athin layer (e.g. micrometers thick) of metal sometimes placed betweentwo other metals. It is done to act as a barrier to protect either oneof the metals from corrupting the other. Example barrier layer 300A,300B, 300C materials include, but are not limited to, cobalt, nickel,tungsten, ruthenium, tantalum, tantalum nitride, indium oxide, tungstennitride, and titanium nitride.

In some embodiments, the barrier layer 300A, 300B, 300C may consist ofmaterial with very low thermal conductivity and very high electricalconductivity. Inclusion of a barrier layer 300A, 300B, 300C of thisnature may serve to improve the thermoelectric performance by reducingthermal conductivity, which in turn preserves a larger temperaturedifferential, without sacrificing electrical conductivity. In someembodiments, a barrier layer 300A, 300B, 300C may serve as both adiffusion barrier and a thermal barrier. Example barrier layer materialswith these properties include, but are not limited to, Indium Antimonide(InSb) and other skutterides, which have low thermal conductivity andhigh electrical conductivity.

The surface plating layer 302 may be a conductive layer applied to asolid material using a chemical technique. Examples include, but are notlimited to, electroless nickel immersion gold (i.e. ENIG), and solder(i.e. HASL, or hot air solder leveling). The surface plating layer 302may serve as a protective layer of the P-designated conductive pads 108and the N-designated conductive pads 106 while providing good electricalconductivity.

The conductive paste 304 may be a powdered metal compound suspended in aviscous medium. Examples include, but are not limited to, silver orother conductive ink, silver paste, nano metal ink, and solder paste.The conductive paste 304 may be a liquid metal, such asgallium-containing alloys, with very low melting points which form aeutectic which is liquid at room temperature. In various embodiments, aconductive paste 304 may be applied using a screen printing process,where the paste is applied using a mask or stencil.

FIG. 4 is a lower patterned mask view 450 of the flexible thermoelectricdevice 100 of FIG. 1, illustrating a lower patterned mask 400 aligned ontop of a metal clad 103 in preparation for forming a lower conductionlayer 104 with electrically conductive pads 107 and lower electricallyconductive leads 110, according to one embodiment. In addition, FIG. 4depicts the top view of lower patterned mask 452. Particularly, FIG. 4builds on FIG. 1, and further adds a lower patterned mask 400 and alayer of metal 402.

The lower patterned mask 400 may be a plurality of first areascorresponding to a plurality of electrically conductive pads 107 and aplurality of lower electrically conductive leads 110. The lowerpatterned mask 400 may be aligned on the top of a metal clad 103 of theflexible thermoelectric device 100.

The layer of metal 402 in a metal clad 103 may form the plurality ofelectrically conductive pad 107 and lower electrically conductive lead110 when a metal outside the plurality of the first areas is removed inthe layer of metal 402.

FIG. 5 is a P-designated mask view 550 of the flexible thermoelectricdevice 100 of FIG. 1, illustrating a P-designated mask 500 aligned ontop of the lower conduction layer 104 in preparation for forming P-typeconduits 114 on top of P-designated conductive pads 108, according toone embodiment. In addition, FIG. 5 shows a top view of P-designatedmask 552. Particularly, FIG. 5 builds on FIG. 1, and further adds aP-designated mask 500.

The P-designated mask 500 may be a mask used to deposit, grow, etchand/or remove material to form one or more layer of P-typethermoelectric material 202 of one or more P-type conduit 114 above theP-designated conductive pad 108. It may also be a mask to deposit, grow,etch and/or remove material to form one or more barrier layer (e.g.,barrier layer 300A, 300B or 300C) above the P-designated conductive pad108. The P-designated mask 500 may have a first pattern corresponding tothe plurality of P-designated conductive pads 108 of the lowerconduction layer 104, such that the plurality of P-designated conductivepads 108 may be exposed through the P-designated mask 500.

FIG. 6 is an N-designated mask view 650 of the flexible thermoelectricdevice 100 of FIG. 1, illustrating an N-designated mask 600 aligned ontop of the lower conduction layer 104 in preparation for forming N-typeconduits 112 on top of N-designated conductive pads 106, according toone embodiment. FIG. 6 further shows a top view of N-designated mask652. Particularly, FIG. 6 builds on FIG. 1, and further adds anN-designated mask 600.

The N-designated mask 600 may be a mask used to deposit, grow, etchand/or remove material to form one or more layer of N-typethermoelectric material(s) 200 of the N-type conduit 112. TheN-designated mask 600 may have a first pattern based on the plurality ofN-designated conductive pads 106 of the lower conduction layer 104 suchthat the plurality of N-designated conductive pads 106 of the lowerconduction layer 104 may be exposed through the N-designated mask 600.

FIG. 7 is a PN-designated mask view 750 of the flexible thermoelectricdevice 100 of FIG. 1, illustrating a PN-designated mask 700 aligned ontop of the lower conduction layer 104 in preparation for forming abarrier layer (e.g., barrier layer 300A, 300B and 300C) on P-typeconduits 114 and N-type conduits 112, according to one embodiment. FIG.7 further shows a top view of PN-designated mask 752. Particularly, FIG.7 builds on FIG. 1, and further adds a PN-designated mask 700.

The PN-designated mask 700 may be a mask used to deposit, grow, etchand/or remove material to form one or more layer of N-typethermoelectric material 200, P-type thermoelectric material 202, and/orother material for a barrier layer (e.g., barrier layer 300A, 300B and300C). The PN-designated mask 700 may have a pattern such that at leastone of the N-designated conductive pads 106 and P-designated conductivepads 108 of the lower conduction layer 104 may be exposed through thePN-designated mask 700.

FIG. 8 a flexible coverlay view 850 of the flexible thermoelectricdevice 100 of FIG. 1, illustrating a flexible coverlay 119 with drilledcontact holes 122 aligned on top of P-type conduits 114 and N-typeconduits 112 in preparation for lamination, according to one embodiment.Further, FIG. 8 shows a top view of flexible coverlay 852.

During lamination, the flexible coverlay 119 is pressed against thelower conduction layer 104 under controlled conditions so that the layerof adhesive (e.g., thermal insulator (adhesive) 120)) deforms and fillsa space around each of the P-type conduits 114 and N-type conduits 112.The controlled conditions may include temperature control, and/orpressure control.

FIG. 9 is an upper patterned mask view 950 of the flexiblethermoelectric device 100 of FIG. 1, illustrating an upper patternedmask 900 aligned on top of the contact holes 122 in the flexiblecoverlay 119 in preparation for forming an upper conduction layer 124 ontop of and through the flexible coverlay 119 using the upper patternedmask 900, according to one embodiment. FIG. 9 further shows a top viewof upper patterned mask 952. Particularly, FIG. 9 builds on FIG. 1, andfurther adds an upper patterned mask 900.

The upper patterned mask 900 may be a mask used to deposit, grow, etchand/or remove material to form the upper conduction layer 124. The upperpatterned mask 900 has a plurality of second areas corresponding to theplurality of P-designated contact holes (e.g., contact holes 122) andN-designated contact holes (e.g., contact holes 122), and a plurality ofupper electrically conductive leads 128.

FIG. 10 is an upper dielectric layer view 1050 of the flexiblethermoelectric device 100 of FIG. 1, illustrating an upper dielectriclayer 130 formed on top of the upper conduction layer 124 and theinternal dielectric layer 118, according to one embodiment. Further,FIG. 10 shows a top view of upper dielectric layer 1052. The flexiblethermoelectric device 100 may be sealed and protected with the upperdielectric layer 130. The upper dielectric layer 130 may be a flexiblepolymer, a polymer composite, a polyimide, a polyacrylate, a polyvinylacetate and/or a mylar. Further, the upper dielectric layer 130 may bean electrical insulator and good thermal conductor having the thermalconductivity value greater than 5 watts per meter kelvin (W/(mK)).

FIG. 11 is a finished view 1150 of the flexible thermoelectric device100 of FIG. 1, according to one embodiment. When finished, the flexiblethermoelectric device 100 may include an upper dielectric layer 130, aninternal dielectric layer 118, a thermal insulator (adhesive) 120 and alower dielectric layer 102.

The finished flexible thermoelectric device 100 may be produced byforming a lower conduction layer 104 on top of a lower dielectric layer102, aligning an N-designated mask 600 on top of the lower conductionlayer 104, forming a plurality of N-type conduits 112 each on top of oneof the N-designated conductive pads 106, aligning a P-designated mask500 on top of the lower conduction layer 104, forming a plurality ofP-type conduits 114 each on top of one of the P-designated conductivepads 108, laminating a layer of thermal insulator on top of and aroundthe plurality of N-type conduits 112 and P-type conduits 114, drilling aplurality of contact holes 122 each through the internal dielectriclayer 118 and the layer of thermal insulator, forming an upperconduction layer 124 on top of the internal dielectric layer 118, andforming an upper dielectric layer 130 on top of the upper conductionlayer 124, according to one embodiment.

FIG. 12 is a cut away view 1250 of the flexible thermoelectric device100 of FIG. 1 with the dielectrics (e.g., lower dielectric layer 102,internal dielectric layer 118 and upper dielectric layer 130) andthermal insulators (e.g., thermal insulator (adhesive) 120) removed,illustrating the thermoelectric conduits (e.g., N-type conduits 112and/or P-type conduits 114) electrically connected in series via theupper conduction layer 124 and lower conduction layer 104, according toone embodiment.

FIG. 13 is an electrical conduction path view 1350 of the flexiblethermoelectric device 100 of FIG. 1, illustrating the electricalconduction path 1300 through the interconnected P-type conduits 114 andN-type conduits 112 of the flexible thermoelectric device 100, accordingto one embodiment. Particularly, FIG. 13 builds on FIG. 1, and furtheradds an electrical conduction path 1300.

The electrical conduction path 1300 is a zig-zag pattern that goesthrough the P-type conduits 114 and N-type conduits 112 in the activelayer 116, the electrically conductive pads 107 and the lowerelectrically conductive leads 110 in the lower conduction layer 104, andthe electrically conductive contact 126 and upper electricallyconductive lead 128 in the upper conduction layer 124. Although anelectrical energy may flow momentarily in the vertical direction in theelectrical conduction path 1300, the net flow of the electrical energyis in the horizontal direction in the flexible thermoelectric device100.

FIG. 14 is a thermal conduction path view 1450 of the flexiblethermoelectric device 100 of FIG. 1, illustrating a plurality of thermalconduction paths 1400 each going through one of the P-type conduits 114and N-type conduits 112 of the flexible thermoelectric device, accordingto one embodiment. Particularly, FIG. 14 builds on FIG. 1, and furtheradds a thermal conduction path 1400.

The thermal conduction paths 1400 are vertical. Heat energy movesthrough each of the P-type conduits 114 and N-type conduits 112 withoutleaking into other neighboring conduits.

Consider an example case. Suppose a temperature gradient exists betweenthe two sides (e.g., the lower side and the upper side in FIG. 11 andFIG. 12) of the flexible thermoelectric device 100. Without loss ofgenerality, suppose the temperature on the lower side in FIG. 11 andFIG. 12 is higher than the upper side by 10 degrees Kelvin. As the lowerdielectric layer 102 is a good thermal conductor, the temperature at thelower conduction layer 104 may be similar to the lower side temperature.Similarly, as the upper dielectric layer 130 is a good thermalconductor, the temperature at the upper conduction layer 124 may besimilar to the upper side temperature. Thus the temperature gradient onthe two sides of the P-type conduits 114 and N-type conduits 112 may besimilar to the outside temperature gradient (10 degree Kelvin in theexample). As the P-type conduits 114 and N-type conduits 112 aresurrounded by thermal insulators (adhesive) 120, the heat energy maytravel through the P-type conduits 114 and N-type conduits 112vertically from hot to cold without leaking to other surroundingconduits. The temperature gradient causes the holes in the P-typeconduits 114 to move from cold to hot, and the electrons in the N-typeconduits 112 to move from hot to cold generating electric current andclosing the loop. The P-type conduits 114 and N-type conduits 112 areelectrically connected in series such that their voltages are added tobuild a meaningful combined voltage. The net direction of the electriccurrent is in the horizontal direction while keeping the direction ofheat flow constant in vertical direction from hot to cold.

FIG. 15A shows a process flow 1550 to produce a flexible thermoelectricdevice 100 of FIG. 1, according to one embodiment.

In operation 1502, the lower conduction layer 104 may be formed on topof the lower dielectric layer 102.

In operation 1504, the lower conduction layer 104 may include aplurality of electrically conductive pads 107 and a plurality of lowerelectrically conductive leads 110, according to one embodiment.

In operation 1506, the plurality of electrically conductive pads 107 mayinclude a plurality of N-designated conductive pads 106 and a pluralityof P-designated conductive pads 108, according to one embodiment.

In operation 1508, each of the lower electrically conductive leads 110may connect a pair of neighboring N-designated conductive pad 106 andP-designated conductive pad 108, according to one embodiment.

In operation 1510, an N-designated mask 600 may be aligned on top of thelower conduction layer 104, according to one embodiment.

In operation 1512, the N-designated mask 600 may have a first patternbased on the plurality of N-designated conductive pads 106 of the lowerconduction layer 104 such that the plurality of N-designated conductivepads 106 of the lower conduction layer 104 may be exposed through theN-designated mask 600, according to one embodiment.

In operation 1514, a plurality of N-type conduits 112 may be formed eachon top of one of the N-designated conductive pads 106 exposed throughthe N-designated mask 600 based on the first pattern, according to oneembodiment.

FIG. 15B is a continuation of the process flow 1550 of FIG. 15A,according to one embodiment.

In operation 1516, a P-designated mask 500 may be aligned on top of thelower conduction layer 104, according to one embodiment.

In operation 1518, the P-designated mask 500 may have a second patternbased on the plurality of P-designated conductive pads 108 of the lowerconduction layer 104, according to one embodiment.

In operation 1520, a plurality of P-type conduits 114 may be formed eachon top of one of the P-designated conductive pads 108 exposed throughthe P-designated mask 500 based on the second pattern, according to oneembodiment.

In operation 1522, a layer of thermal insulator 120 may be laminated ontop of and around the plurality of N-type conduits 112 and P-typeconduits 114 with an internal dielectric layer 118 on top of the thermalinsulator 120 layer, according to one embodiment.

In operation 1524, a plurality of contact holes 122 may be drilled eachthrough the internal dielectric layer 118 and the thermal insulator 120layer above one of the N-type conduits 112 and P-type conduits 114,according to one embodiment.

In operation 1526, an upper conduction layer 124 may be formed on top ofthe internal dielectric layer 118 and through the plurality of contactholes 122. The upper conduction layer 124 may include a plurality ofelectrically conductive contacts 126 and a plurality of upperelectrically conductive leads 128. Each of the electrically conductivecontacts 126 is coupled to the top of one of the N-type conduits 112 andP-type conduits 114 through one of the contact holes 122. Each of theupper electrically conductive leads 128 connects a pair of neighboringelectrically conductive contact 126, according to one embodiment.

In operation 1528, an upper dielectric layer 130 may be formed on top ofthe upper conduction layer 124, according to one embodiment.

FIG. 16A illustrates another process flow 1650 to produce a flexiblethermoelectric device 100 of FIG. 1 from directly depositedthermoelectric materials, according to one embodiment.

In operation 1602, a lower patterned mask 400 may be aligned on top of aflexible metal clad 103, according to one embodiment.

In operation 1604, the lower patterned mask 400 may include a pluralityof first areas corresponding to a plurality of electrically conductivepads 107 and a plurality of lower electrically conductive leads 110,according to one embodiment.

In operation 1606, the flexible metal clad 103 may include a layer ofmetal 402 on top of a lower dielectric layer 102, according to oneembodiment.

In operation 1608, the plurality of electrically conductive pads 107 mayinclude a plurality of P-designated conductive pads 108 and a pluralityof N-designated conductive pads 106, according to one embodiment.

In operation 1610, each of the lower electrically conductive leads 110may link a pair of P-designated conductive pad 108 and N-designatedconductive pad 106, according to one embodiment.

In operation 1612, a lower conduction layer 104 of the flexiblethermoelectric device 100 may be formed with the plurality ofP-designated conductive pads 108, the plurality of N-designatedconductive pads 106 and the plurality lower electrically conductiveleads 110 based on the lower patterned mask 400, according to oneembodiment.

In operation 1614, a P-designated mask 500 may be aligned on top of thelower conduction layer 104 of the flexible metal clad 103, according toone embodiment.

In operation 1616, the P-designated mask 500 may have a first patterncorresponding to the plurality of P-designated conductive pads 108 ofthe lower conduction layer 104 such that the plurality of P-designatedconductive pads 108 are exposed through the P-designated mask 500,according to one embodiment.

In operation 1618, a plurality of P-type conduits 114 may be formed withone or more layer of P-type thermoelectric material 202 using theP-designated mask 500 and one or more kind of the P-type thermoelectricmaterial 202, according to one embodiment.

FIG. 16B is continuation of the process flow 1650 of FIG. 16A, accordingto one embodiment.

In operation 1620, each of the P-type conduits 114 may be located on topof one of the plurality P-designated conductive pads 108 of the flexiblemetal clad 103 exposed through the P-designated mask 500, according toone embodiment.

In operation 1622, an N-designated mask 600 may be aligned on top of thelower conduction layer 104 of the flexible metal clad 103, according toone embodiment.

In operation 1624, the N-designated mask 600 may have a second patterncorresponding to the plurality of N-designated conductive pads 106 ofthe lower conduction layer 104 such that the plurality of N-designatedconductive pads 106 are exposed through the N-designated mask 600,according to one embodiment.

In operation 1626, a plurality of N-type conduits 112 may be formed withone or more layer of N-type thermoelectric material 200 using theN-designated mask 600 and one or more kind of N-type thermoelectricmaterial 200, according to one embodiment.

In operation 1628, each of the N-type conduits 112 may be located on topof one of the N-designated conductive pads 106 of the flexible metalclad 103 exposed through the N-designated mask 600, according to oneembodiment.

In operation 1630, a plurality of P-designated contact holes (e.g.,contact holes 122) may be drilled through a flexible coverlay 119 eachcorresponding to one of the P-type conduits 114, and a plurality ofN-designated contact holes (e.g., contact holes 122) may be drilledthrough the flexible coverlay 119 each corresponding to one of theN-type conduits 112, according to one embodiment.

In operation 1632, the flexible coverlay 119 may include an internaldielectric layer 118 on top of a layer of adhesive, according to oneembodiment.

In operation 1634, the plurality of P-type conduits 114 and N-typeconduits 112 of the lower conduction layer 104 may be aligned under theflexible coverlay 119 such that each of the P-designated contact holes(e.g., contact holes 122) of the flexible coverlay 119 is directly aboveone of the P-type conduits 114 and each of the N-designated contactholes (e.g., contact holes 122) of the flexible coverlay 119 is directlyabove one of the N-type conduits 112, according to one embodiment.

FIG. 16C is continuation of the process flow 1650 of FIG. 16A, accordingto one embodiment.

In operation 1636, the flexible coverlay 119 may be laminated on top ofthe lower conduction layer 104 by pressing the flexible coverlay 119against the lower conduction layer 104 under controlled conditions,according to one embodiment.

In operation 1638, the flexible coverlay 119 may be aligned under anupper patterned mask 900, according to one embodiment.

In operation 1640, the upper patterned mask 900 may have a plurality ofsecond areas corresponding to the plurality of P-designated contactholes (e.g., contact holes 122) and N-designated contact holes (e.g.,contact holes 122) and a plurality of upper electrically conductiveleads 128, according to one embodiment.

In operation 1642, an upper conduction layer 124 of the flexiblethermoelectric device 100 may be formed on top of and through theflexible coverlay 119 using the upper patterned mask 900, according toone embodiment.

In operation 1644, the flexible thermoelectric device 100 may be sealedand protected with an upper dielectric layer 130, according to oneembodiment.

FIG. 17 illustrates yet another process flow 1750 to produce a flexiblethermoelectric device(s) 100 of FIG. 1, according to one embodiment.

In operation 1702, a plurality of P-designated contact holes (e.g.,contact holes 122) may be drilled through a flexible coverlay 119 eachcorresponding to a P-type conduit 114 on the top of a lower conductionlayer 104 of the flexible thermoelectric device 100. A plurality ofN-designated contact holes (e.g., contact holes 122) may be drilledthrough the flexible coverlay 119 each corresponding to an N-typeconduit 112 on top of the lower conduction layer 104, according to oneembodiment.

In operation 1704, the flexible coverlay 119 may include a layer ofadhesive under an internal dielectric layer 118.

In operation 1706, the plurality of P-type conduits 114 and N-typeconduits 112 may be aligned with respect to and under the flexiblecoverlay 119, according to one embodiment.

In operation 1708, each of the P-designated contact holes (e.g., contactholes 122) of the flexible coverlay 119 may be directly above one of theP-type conduits 114 and each of the N-designated contact holes (e.g.,contact holes 122) of the coverlay may be directly above one of theN-type conduits 112, according to one embodiment.

In operation 1710, each of the P-type conduits 114 may be electricallyconnected to one of the N-type conduits 112 through the lower conductionlayer 104 above a lower dielectric layer 102 of the flexiblethermoelectric device 100, according to one embodiment.

In operation 1712, the flexible coverlay 119 may be laminated on top ofthe lower conduction layer 104 by pressing the flexible coverlay 119against the lower conduction layer 104 under controlled conditions,according to one embodiment.

In operation 1714, the flexible coverlay 119 may be aligned under anupper patterned screen (e.g. upper patterned mask 900), according to oneembodiment.

In operation 1716, the upper patterned screen (e.g. upper patterned mask900) may include a plurality of first areas corresponding to theplurality of P-designated contact holes (e.g., contact holes 122) andN-designated contact holes (e.g., contact holes 122), and a plurality ofsecond areas corresponding to a plurality of upper electricallyconductive leads 128, according to one embodiment.

In operation 1718, the upper conduction layer 124 of the flexiblethermoelectric device 100 may be screen printed on top of and throughthe flexible coverlay 119 by pressing a conductive paste 304 through theupper patterned screen (e.g. upper patterned mask 900), according to oneembodiment.

In operation 1720, the flexible thermoelectric device 100 may be sealedand protected with an upper dielectric layer 130, according to oneembodiment.

FIG. 18 is a wearable device view 1850 of the flexible thermoelectricdevice 100 of FIG. 1, illustrating two examples of the flexiblethermoelectric device 100 harvesting energy for wearable applications,according to one embodiment. Particularly, FIG. 18 builds on FIG. 1, andfurther adds smart gadgets 1800A and 1800B, rechargeable batteries 1802Aand 1802B, wearable devices 1804A and 1804B.

In the examples, both smart gadgets 1800A and 1800B (e.g., smart watch,smart clothing) may have wearable devices 1804A and 1804B (e.g.,embedded processor and memory with user interface, wearable computer,body networked computer) embedded and powered by rechargeable batteries1802A and 1802B (e.g. lithium ion (Li ion) battery, nickel metal hydride(NiMh) battery, nickel-cadmium (NiCd) battery, nickel-zinc (NiZn)battery, lead-acid battery, fuel cell, flow cell, electrolytic cells,galvanic cells, voltaic pile, wet cell, dry cell, reserve battery). Theflexible thermoelectric device 100 may be embedded in the smart gadgetsto be used at locations (e.g., wrist band, arm band, head band, sock,shirt, clothing, fabric, accessories) where the flexible thermoelectricdevice 100 may be subjected to temperature gradients (e.g., between thehuman body temperature and the ambient temperature) such that the activelayer 116 of the flexible thermoelectric device 100 may generateelectricity from the temperature gradient. The flexible thermoelectricdevice 100 may be connected to the wearable devices 1804A and 1804B sothat the generated electricity may be used to power the wearable devices1804A and 1804B. The flexible thermoelectric device 100 may be connectedto the rechargeable batteries 1802A and 1802B so that the generatedelectricity may be stored in the batteries 1802A and 1802B.

The smart gadgets 1800A and/or 1800B may be any wearable device on thebody of a human being and/or a creature such as smart phone, smart phoneaccessory, battery charger, tablet, portable computer, portable scanner,portable tools, remote control, game device, game accessory, smartwatch, smart glass, smart arm band, smart wrist band, smart pin, smartcomb, smart pen, smart name card, smart purse, smart wallet, smart belt,smart necklace, smart ring, smart email ring, smart hat, smart cap,smart scarf, smart garment, smart fabric, smart shirt, smart pants,smart clothing, smart glove, smart underwear, smart sock, smart shoe,smart bag, smart backpack, smart pet accessory, smart animal accessory,etc.

The smart gadgets 1800A and/or 1800B may also be any device to be placedin, on, through, and/or around any devices and/or systems experiencingtemperature gradient among some sides, such as land vehicles, watervehicles, marine vehicles, submarine vehicles, aeronautic vehicles,space vehicles, volcano devices, engines, computers, machineries andcomponents, electromagnetic devices, cables, wires, antennas, solarpanels, lamps and lighting devices, heaters, air conditioners, tubing,pipes, water pipes, displays, billboards, TVs, DVDs, audio systems,cooking devices, baking devices, cups, plates, spoons, utensils,building materials, windows, doors, walls, boards, tables, chairs,furniture, floor, ceiling, deck furniture, swimming pool accessories,etc.

The rechargeable battery 1802A and/or 1802B may be a device consistingof two or more electrochemical cells that converts stored chemicalenergy into electrical energy. During recharging, the rechargeablebattery 1802A and/or 1802B converts electrical energy into storedchemical energy. The rechargeable battery 1802A and/or 1802B may also bea device that converts stored energy into electrical energy. The storedenergy may be electrical energy or another form of energy. Duringrecharging, the rechargeable battery 1802A and/or 1802B convertselectrical energy into stored energy. The rechargeable battery 1802Aand/or 1802B may be in arbitrary shape and size.

The wearable device 1804A and/or 1804B may have a processor, a memory, adisplay, a sensor, an actuator, a user interface, a network interface, awireless network interface, and/or other interface.

Other features of the present embodiments will be apparent from theaccompanying drawings and from the detailed description that follows.

Low efficiency, high operating temperature combined with higher costforbid current thermoelectric devices for wider market adoption. Lowefficiency may relegate thermoelectric devices to a few applicationswhere their simplicity and ruggedness may outweigh the inefficiency,such as sensors and waste-heat-energy converters. The potential forthermoelectric devices, however, may be much greater. If theirefficiency may be increased and reduce the operational temperatures nearroom temperature (300 K), thermoelectric devices may begin to supplantmechanical compressor refrigeration systems, gasoline generators,geothermal power production, and more. Thermoelectric devices may play asignificant role in the energy production, home heating/cooling andgeneral energy management of the future.

Low thermal conductivity with higher electrical conductivity is neededfor higher ZT. Unfortunately there are no single materials that possesssimultaneously higher electrical conductivity and lower thermalconductivity. Most of the recent efforts in research community thus havebeen reducing thermal conductivity by phonon blocking and/or phononscattering and/or reducing phonon free mean path.

Thermoelectric devices may be made out of bulk material in the form ofingots and/or pellets. The ingot may be formed from liquid melt and/orfrom the powder metallurgy route. Each pellet may be attached on asubstrate and form a module.

Recent advancements may be made using a thin-film process that allowsforming micro bumps using common semiconductor equipment. This allowsthousands of micro bumps to form a thermoelectric device to producemeaningful voltage and power output.

Metal particles may be incorporated in a thermoelectric material to forma composite structure. Nanophase metal particles in a polymer matrix maybe utilized to form a composite thermoelectric device. Ceramicnanoparticles may be introduced as phonon scattering centers in athermoelectric device to improve the figure of merit (ZT), which mayoccur with nano-carbon material units in a thermoelectric matrix.

Quantum super lattice structures may be limited to expensive compositethermoelectric materials and methods and thus limiting the wide spreaduse of such devices in common market place. Thermoelectric componentsmay be placed in series, but the thermal conductivity may be diminishedbecause the interconnections between the semiconductors may createthermal shorting.

There may be no material that possesses high electrical conductivity andlow thermal conductivity simultaneously. Another limitation in currentart is each material may behave differently at different temperatures. Athermoelectric cell approach with a flexible substrate may permitstacking. Stacking allows combining different materials with differentproperties, and may be with or without a spacer. Thermoelectric elementsmay be connected electrically in series, but thermally in parallelacross a temperature gradient. Stacking may allow manufacturers tocontrol electrical conductivity and thermal conductivity independently,and may be able to stack different materials. In one embodiment, thestacked layer may be a single N-type or P-type stack. Additionally,there may be a super lattice for each layer.

A refrigerating effect may be obtained in the flexible thermoelectricdevice 100 by passing current along a circuit containing dissimilarmaterials, according to one embodiment. Heat may be absorbed at onejunction of the two materials and heat may be released at the otherjunction, according to one embodiment.

The transfer of heat may be caused by the change in electron energylevels when electrons access the conduction band as defined by quantumphysics. The conduction band varies with each material, which means thatconducting electrons in some materials may be at a higher energy levelthan in other materials. When electrons pass down a circuit ofdissimilar materials, the electrons alternately extract energy and/orrelease energy with each change in the conduction band.

The desired refrigerating effect may occur when electrons move to ahigher energy level upon change of material. A reverse effect may alsooccur when electricity is generated from a circuit of dissimilarmaterials that may be exposed to a temperature differential. This is thephysical principle that forms the basis of the thermocouple and is knownas the Seebeck effect. The Peltier and Seebeck effects are complementarymanifestations of the same physical phenomenon.

There are other applications for the flexible thermoelectric device 100.Voltage generation from temperature differentials in a wide array ofsituations in different fields offer the potential for application ofthe flexible thermoelectric device 100. The flexible thermoelectricdevice 100 may be used in medical applications, e.g. cochlear hearingreplacements and devices, nerve stimulation implants; consumerapplications, e.g. watches, self-powered toys and novelties; militaryapplications, e.g. wireless personal area networks, ammunition safetysensors, space programs, building environmental control and security.

The flexible thermoelectric device 100 may be integrated to powerindustrial and/or commercial devices, e.g. wireless sensor networks,automobile tire pressure monitors, wireless HVAC sensors, wirelesslighting an energy controls, wireless industrial process controlsensors, and oil and gas well head sensors. The flexible thermoelectricdevice 100 may provide ecological and/or energy applications, e.g.secondary power generation/recovery, electric generation grid devicemonitor sensors, and environmental condition sensors.

In the field of building automation, the flexible thermoelectric device100 may have practical applications in security, HVAC, automatic meterreading, lighting control, and access control. In the area of personalhealth care, the layer composite may have applications in patientmonitoring and fitness monitoring. The flexible thermoelectric device100 may have industrial control applications, e.g. asset managementprocess control and environmental energy management.

Consumer electronics applications may include televisions, VCRs, DVD/CDremotes and/or players, mobile phones, tablets, laptops, householdappliances, computer mice, keyboards, joysticks, and/or personalcomputers and computing peripherals. Residential/light commercialcontrol applications of the layer composite may include security, HVAC,lighting control, access control, and/or lawn & garden irrigationsystems.

In one embodiment, while thermally conductive, the flexiblethermoelectric device 100 may effectively maintain the temperaturedifferential between opposite ends of the flexible thermoelectric device100. Thereby, the flexible thermoelectric device 100 may createtemperature differentials that may be persistent and thus may optimizethe voltage generation from a temperature gradient.

The resistance to heat transfer attributable to the flexiblethermoelectric device 100 perpetuates the overall temperaturedifferential and thus may effectively sustain the temperature gradientacross each stratum of the thermoelectric layers and accordingly theflexible thermoelectric device 100 as a whole. Because of thisresistance to heat transfer, the flexible thermoelectric device 100 mayserve as a more efficient means of voltage generation since thetemperature differentials at each layer of thermoelectric material maynot require additional heat sinks and/or energy-intensive coolingtechniques that may be employed to maintain the temperaturedifferential.

While serving as a thermoelectric device, the material composition ofthe thermoelectric layer may be altered and adjusted according to thespecific needs of each application. The flexible thermoelectric device100 is material independent, according to one embodiment. If theapplication of the flexible thermoelectric device 100 requires aspecific temperature range, e.g. environments with temperatures higherthan 800 degrees K, then a particular material may be employed in thethermoelectric layers. For example, Bismuth Telluride may be appropriatein one temperature range, while Silicon Germanium may be more suitablein another temperature.

The thermoelectric layer may include whatever material is mostappropriate and best suited to the conditions of the application.Temperature may be one variable. Other factors may be electricalconductivity, malleability, texture, etc. Because the flexiblethermoelectric device 100 is material independent, the material bestsuited for the relevant application may be chosen, thus optimizing thevoltage generation and other properties for each application.

Additionally, because the flexible thermoelectric device 100 is materialindependent and because of the effectiveness of the flexiblethermoelectric device 100 in maintaining a temperature gradient acrossits strata, multiple types of materials may be employed in composing thethermoelectric layer. For example, the thermoelectric layer may containCu₂Te, Bi₂Te₃, and/or Sb₂Te₃, all in one cell.

Because the thermoelectric layers may maintain a temperaturedifferential effectively, materials impractical at one temperature maystill be used in the thermoelectric layer at a different depth with adifferent temperature where the material may be practical. For example,if the hot surface of the flexible thermoelectric device 100 precludesuse of one material because it may melt and/or not be as thermally orelectrically conductive at that temperature, that material may still beutilized at the cooler end of the flexible thermoelectric device 100because the flexible thermoelectric device 100 maintains the temperaturedifferential and the material may be used toward the cool surface of theflexible thermoelectric device 100. Thus, the flexible thermoelectricdevice(s) 100 characteristic of sustaining the temperature gradient maypermit the combination of different materials and thereby optimize theinherent properties of component materials.

The flexible thermoelectric device 100 may have a stratum-likestructure, according to one embodiment. Because the flexiblethermoelectric device 100 inhibits the flow of heat across the layers,there may be a relatively smaller temperature differential per eachlayer. However, because the flexible thermoelectric device 100 maycomprise as many layers as a manufacturer and/or consumer desire,according to one embodiment, the temperature differentials across eachlayer may sum up to a larger overall temperature differential across theentire device.

The flexible thermoelectric device 100 may harvest energy from wasteheat at lower costs with a higher ZT value, higher efficiency, lowermanufacturing costs, and may be easily integrated into existingmanufacturing process systems for applications. Furthermore, because ofits flexibility, the device may be used in other wearable electronics toutilize body heat.

A number of embodiments have been described. Nevertheless, it will beunderstood that various modifications may be made without departing fromthe spirit and scope of the claimed invention. In addition, the logicflows depicted in the figures do not require the particular order shown,or sequential order, to achieve desirable results. In addition, othersteps may be provided, or steps may be eliminated, from the describedflows, and other components may be added to, or removed from, thedescribed systems. Accordingly, other embodiments are within the scopeof the following claims. Furthermore, the specification and/or drawingsmay be regarded in an illustrative rather than a restrictive sense.

What is claimed is:
 1. A method of producing a flexible thermoelectricdevice comprising: forming a lower conduction layer on top of a lowerdielectric layer, with the lower conduction layer comprising a pluralityof electrically conductive pads and a plurality of lower electricallyconductive leads, wherein the plurality of electrically conductive padscomprise a plurality of N-designated conductive pads and a plurality ofP-designated conductive pads, and wherein each of the lower electricallyconductive leads connects a pair of neighboring N-designated conductivepad and P-designated conductive pad; aligning an N-designated mask ontop of the lower conduction layer, wherein the N-designated mask has afirst pattern based on the plurality of N-designated conductive pads ofthe lower conduction layer such that the plurality of N-designatedconductive pads of the lower conduction layer are exposed through theN-designated mask; forming a plurality of N-type conduits each on top ofone of the N-designated conductive pads exposed through the N-designatedmask based on the first pattern; aligning a P-designated mask on top ofthe lower conduction layer, wherein the P-designated mask has a secondpattern based on the plurality of P-designated conductive pads of thelower conduction layer such that the plurality of P-designatedconductive pads of the lower conduction layer are exposed through theP-designated mask; forming a plurality of P-type conduits each on top ofone of the P-designated conductive pads exposed through the P-designatedmask based on the second pattern; laminating a layer of thermalinsulator on top of and around the plurality of N-type conduits andP-type conduits, such that the thermal insulator to fill at least aspace around each of the N-type conduits and P-type conduits, with aninternal dielectric layer on top of the layer of thermal insulator;drilling a plurality of contact holes each through the internaldielectric layer and the layer of thermal insulator above one of theN-type conduits and P-type conduits; forming an upper conduction layeron top of the internal dielectric layer and through the plurality ofcontact holes comprising a plurality of electrically conductive contactseach coupled to the top of one of the N-type conduits and P-typeconduits through one of the contact holes, and a plurality of upperelectrically conductive leads each connecting a pair of neighboringelectrically conductive contacts; and forming an upper dielectric layeron top of the upper conduction layer, wherein at least a portion of eachof the electrically conductive contacts is between the internaldielectric layer and the upper dielectric layer, wherein each of theN-type conduits and P-type conduits is a thin film thermoelectricconduit, with each of the N-type conduits comprising at least one N-typethermoelectric material, and each of the P-type conduits comprising atleast one P-type thermoelectric material, wherein each of the N-typeconduits is electrically connected to one of the P-type conduits in thelower conduction layer and to another one of the P-type conduits in theupper conduction layer, and each of the P-type conduits is electricallyconnected to one of the N-type conduits in the lower conduction layerand to another one of the N-type conduits in the upper conduction layersuch that the plurality of N-type conduits and P-type conduits areelectrically connected in series, and wherein each of the N-typeconduits and P-type conduits is thermally insulated so that a heatenergy flows vertically through the thin film thermoelectric conduitwithout leaking to other thin film thermoelectric conduits on the sides.2. The method of claim 1: wherein each dielectric layer has a thermalconductivity value; wherein the internal dielectric layer is anelectrical insulator and a poor thermal conductor having the thermalconductivity value less than 1 watt per meter kelvin (W/(mK)), andwherein both the upper dielectric layer and the lower dielectric layerare electrical insulators and good thermal conductors having the thermalconductivity value greater than 5 watts per meter kelvin (W/(mK)). 3.The method of claim 1, wherein the thin film thermoelectric conduitscomprise at least one layer of thermoelectric material with a combinedthickness no greater than 50 microns.
 4. The method of claim 1, furthercomprising: forming a barrier layer through at least one of theN-designated mask, the P-designated mask, and a PN-designated mask withat least one of the N-designated conductive pads and P-designatedconductive pads exposed, such that the barrier layer is between at leastone of: different layers of thermoelectric material within at least onethin film thermoelectric conduit, an electrically conductive pad and asecond thin film thermoelectric conduit, and an electrically conductivecontact and a third thin film thermoelectric conduit, wherein thebarrier layer is electrically conductive and has a higher meltingtemperature than either of the substances being separated by the barrierlayer.
 5. The method of claim 1, wherein: at least one of: the formingof the lower conduction layer, the forming of the N-type conduits, theforming of the P-type conduits, the forming of the upper conductionlayer, and the forming of the upper dielectric layer to comprise atleast one of a vacuum deposition, a sputter deposition, a chemical vapordeposition, a physical vapor deposition, an electrochemical deposition,a molecular beam epitaxy, an atomic layer deposition, an electroplating,a screen printing, an etching, a chemical-mechanical planarization, alithography, another deposition method and an etching method.
 6. Themethod of claim 1, wherein: at least one of: the lower dielectric layer,the internal dielectric layer, and the upper dielectric layer to be atleast one of a flexible polymer, a polymer composite, a polyimide, apolyacrylate, a polyvinyl acetate and a mylar.
 7. The method of claim 1:wherein the plurality of electrically conductive pads are formed from atleast one of a first layer of metal in a first metal clad, a first layerof deposited metal, a first layer of conductive paste, a firstelectroplated layer, and a first surface plating layer; and wherein theplurality of electrically conductive contacts are formed from at leastone of a second layer of metal in a second metal clad, a second layer ofdeposited metal, a second layer of conductive paste, a secondelectroplated layer, and a second surface plating layer.
 8. The methodof claim 1, wherein the lower conduction layer and at least one of theplurality of N-type conduits and the plurality of P-type conduits areannealed before the upper conduction layer is made.
 9. The method ofclaim 1, wherein the aligning of the N-designated mask, the forming ofthe N-type conduits, the aligning of the P-designated mask, and theforming of the P-type conduits, are all accomplished within the samevacuum system while continuing to maintain a vacuum.
 10. A method ofproducing a flexible thermoelectric device comprising: aligning a lowerpatterned mask on top of a flexible metal clad, wherein the lowerpatterned mask comprises a plurality of first areas corresponding to aplurality of electrically conductive pads and a plurality of lowerelectrically conductive leads, and wherein the flexible metal cladcomprises a layer of metal on top of a lower dielectric layer; whereinthe plurality of electrically conductive pads comprise a plurality ofP-designated conductive pads and a plurality N-designated conductivepads; wherein each of the lower electrically conductive leads links apair of P-designated conductive pad and N-designated conductive pad;forming a lower conduction layer of the flexible thermoelectric devicewith the plurality of P-designated conductive pads, the plurality ofN-designated conductive pads and the plurality of lower electricallyconductive leads based on the lower patterned mask using the layer ofmetal of the flexible metal clad by removing a metal outside theplurality of first areas using the lower patterned mask; aligning aP-designated mask on top of the lower conduction layer of the flexiblemetal clad, wherein the P-designated mask has a first patterncorresponding to the plurality of P-designated conductive pads of thelower conduction layer, such that the plurality of P-designatedconductive pads are exposed through the P-designated mask; forming aplurality of P-type conduits with at least one layer of P-typethermoelectric material using the P-designated mask and at least onekind of P-type thermoelectric material, wherein each of the P-typeconduits is located on top of one of the P-designated conductive pads ofthe flexible metal clad exposed through the P-designated mask; aligningan N-designated mask on top of the lower conduction layer of theflexible metal clad, wherein the N-designated mask has a second patterncorresponding to the plurality of N-designated conductive pads of thelower conduction layer, such that the plurality of N-designatedconductive pads are exposed through the N-designated mask; forming aplurality of N-type conduits with at least one layer of N-typethermoelectric material using the N-designated mask and at least onekind of N-type thermoelectric material, wherein each of the N-typeconduits is located on top of one of the N-designated conductive pads ofthe flexible metal clad exposed through the N-designated mask; drillinga plurality of P-designated contact holes through a flexible coverlayeach corresponding to one of the P-type conduits and a plurality ofN-designated contact holes through the flexible coverlay eachcorresponding to one of the N-type conduits; wherein the flexiblecoverlay to comprise an internal dielectric layer on top of a layer ofadhesive; aligning the plurality of P-type conduits and N-type conduitsof the lower conduction layer under the flexible coverlay such that eachof the P-designated contact holes of the flexible coverlay is directlyabove one of the P-type conduits and each of the N-designated contactholes of the flexible coverlay is directly above one of the N-typeconduits; laminating the flexible coverlay on top of the lowerconduction layer by pressing the flexible coverlay against the lowerconduction layer under controlled conditions such that: the layer ofadhesive deforms and fills at least a space around each of the P-typeconduits and N-type conduits, and the flexible coverlay is attached tothe flexible metal clad through the layer of adhesive; aligning theflexible coverlay under an upper patterned mask, wherein the upperpatterned mask has a plurality of second areas corresponding to theplurality of P-designated contact holes and N-designated contact holes,and a plurality of upper electrically conductive leads; forming an upperconduction layer of the flexible thermoelectric device on top of andthrough the flexible coverlay using the upper patterned mask, whereinthe upper conduction layer to comprise: a plurality of P-designatedelectrically conductive contacts each in one of the P-designated contactholes coupled to the top of one of the P-type conduits, a plurality ofN-designated electrically conductive contacts each in one of theN-designated contact holes coupled to the top of one of the N-typeconduits, and the plurality of upper electrically conductive leads eachconnecting a pair of P-designated electrically conductive contact andN-designated electrically conductive contact; sealing and protecting theflexible thermoelectric device with an upper dielectric layer; whereineach of the N-type conduits is electrically connected to one of theP-type conduits in the lower conduction layer and to another one of theP-type conduits in the upper conduction layer, and each of the P-typeconduits is electrically connected to one of the N-type conduits in thelower conduction layer and to another one of the N-type conduits in theupper conduction layer such that the plurality of P-type conduits andN-type conduits are electrically connected in series; wherein each ofthe P-type conduits and N-type conduits is thermally insulated so that aheat energy flows vertically through the conduit without leaking toother conduits on the sides.
 11. A method of producing the flexiblethermoelectric device in claim 10, further comprising: aligning aPN-designated mask above the lower conduction layer of the flexiblemetal clad, wherein the PN-designated mask has a third patterncorresponding to at least one of the P-designated conductive pads andN-designated conductive pads, such that the at least one of theP-designated conductive pads and N-designated conductive pads is exposedthrough the PN-designated mask; and forming at least one barrier layerusing the PN-designated mask such that each barrier layer is between atleast one of: two layers of thermoelectric material, an electricallyconductive pad and a first layer of thermoelectric material, and anelectrically conductive contact and a second layer of thermoelectricmaterial; wherein each barrier layer is electrically conductive and hasa higher melting temperature than either of the substances beingseparated by the barrier layer.
 12. The method of claim 10: wherein atleast one of: the forming of the lower conduction layer, the forming ofthe N-type conduits, the forming of the P-type conduits, the forming ofthe upper conduction layer, and the forming of the upper dielectriclayer to comprise at least one of a vacuum deposition, a sputterdeposition, a chemical vapor deposition, a physical vapor deposition, anatomic layer deposition (ALD), an electroplating, a screen printing,another deposition method and an etching method; wherein at least oneof: the lower dielectric layer, the internal dielectric layer, and theupper dielectric layer to be at least one of a flexible polymer, apolymer composite, a polyimide, a polyacrylate, a polyvinyl acetate anda mylar.
 13. A method of producing the flexible thermoelectric device inclaim 10: wherein each dielectric layer has a thermal conductivityvalue; wherein the internal dielectric layer is an electrical insulatorand a poor thermal conductor having the thermal conductivity value lessthan 1 watt per meter kelvin (W/(mK)), and wherein both the upperdielectric layer and the lower dielectric layer are electricalinsulators and good thermal conductors having the thermal conductivityvalue greater than 5 watts per meter kelvin (W/(mK)).
 14. A method ofproducing the flexible thermoelectric device in claim 10, furthercomprising: wherein a soft mask is used for at least one of the lowerpatterned mask, the P-designated mask, the N-designated mask and theupper patterned mask ; applying a layer of photo-resist to at least oneof the flexible metal clad, the lower conduction layer, the plurality ofP-type conduits, the plurality of N-type conduits, the flexiblecoverlay, and the upper conduction layer of the flexible thermoelectricdevice, aligning the flexible metal clad of the flexible thermoelectricdevice with a photo mask, wherein the photo mask has a fourth patterncorresponding to at least one of the lower patterned mask, theP-designated mask, the N-designated mask and the upper patterned mask,such that a light from a light source behind the photo mask is partiallyblocked by the photo mask according to the fourth pattern on the photomask, exposing at least one of the flexible metal clad, the lowerconduction layer, the plurality of P-type conduits, the plurality ofN-type conduits, the flexible coverlay, and the upper conduction layerof the flexible thermoelectric device and the layer of photo-resist tothe light from the light source through the photo mask, performing atleast one of: forming a layer of at least one of P-type thermoelectricmaterial, N-type thermoelectric material, metal and dielectric on theflexible thermoelectric device according to the fourth pattern on thephoto mask, and etching the layer of at least one of P-typethermoelectric material, N-type thermoelectric material, metal anddielectric on the flexible thermoelectric device according to the fourthpattern on the photo mask; removing any remaining photo-resist.
 15. Amethod of producing the flexible thermoelectric device in claim 10:wherein a hard mask is used for at least one of the lower patternedmask, the P-designated mask, the N-designated mask and the upperpatterned mask; wherein at least one of the lower patterned mask, theP-designated mask, the N-designated mask and the upper patterned mask isa stencil.
 16. A method of producing the flexible thermoelectric devicein claim 10, further comprising: applying an electroless nickelimmersion gold (ENIG) process to surface plate a layer of nickel and alayer of gold over the layer of metal of the flexible metal clad, andcleaning and rinsing with a deionized water.
 17. The method of claim 10,wherein the aligning of the N-designated mask, the forming of the N-typeconduits, the aligning of the P-designated mask, and the forming of theP-type conduits, are all accomplished within the same vacuum systemwhile continuing to maintain a vacuum.
 18. A method of producing aflexible thermoelectric device comprising: drilling a plurality ofP-designated contact holes through a flexible coverlay eachcorresponding to a P-type conduit on top of a lower conduction layer ofthe flexible thermoelectric device, and a plurality of N-designatedcontact holes through the flexible coverlay each corresponding to anN-type conduit on top of the lower conduction layer; wherein theflexible coverlay comprises a layer of adhesive under an internaldielectric layer; aligning the plurality of P-type conduits and N-typeconduits under the flexible coverlay such that each of the P-designatedcontact holes of the flexible coverlay is directly above one of theP-type conduits and each of the N-designated contact holes of theflexible coverlay is directly above one of the N-type conduits; whereineach of the P-type conduits is electrically connected to one of theN-type conduits through the lower conduction layer above a lowerdielectric layer of the flexible thermoelectric device; laminating theflexible coverlay on top of the lower conduction layer by pressing theflexible coverlay against the lower conduction layer under controlledconditions such that: the layer of adhesive deforms and fills at least aspace around each of the P-type conduits and N-type conduits, and theflexible coverlay is attached to the lower conduction layer through thelayer of adhesive; aligning the flexible coverlay under an upperpatterned screen, wherein the upper patterned screen to comprise aplurality of first areas corresponding to the plurality of P-designatedcontact holes and N-designated contact holes, and a plurality of secondareas corresponding to a plurality of upper electrically conductiveleads; screen printing an upper conduction layer of the flexiblethermoelectric device on top of and through the flexible coverlay bypressing a conductive paste through the upper patterned screen suchthat: the conductive paste penetrates each P-designated contact hole toform an electrically conductive contact coupled to the top of one of theP-type conduits, the conductive paste penetrates each N-designatedcontact hole to form another electrically conductive contact coupled tothe top of one of the N-type conduits, and the conductive paste at eachof the second areas forms an upper electrically conductive leadconnecting a pair of electrically conductive contacts; sealing andprotecting the flexible thermoelectric device with an upper dielectriclayer; wherein the plurality of P-type conduits and N-type conduits areelectrically connected in series; wherein each of the P-type conduitsand N-type conduits is thermally insulated so that a heat energy flowsvertically through the conduit without leaking to other conduits on thesides.
 19. A method of producing the flexible thermoelectric device inclaim 18, further comprising: aligning a flexible metal clad under alower patterned mask, wherein the flexible metal clad comprises a layerof metal on top of the lower dielectric layer, and wherein the lowerpatterned mask to comprise a plurality of third areas for a plurality ofP-designated electrically conductive pads, a plurality of N-designatedconductive pads, and a plurality of lower electrically conductive leads;wherein each of the lower electrically conductive leads links a pair ofP-designated conductive pad and N-designated conductive pad; forming thelower conduction layer of the flexible thermoelectric device with theplurality of P-designated conductive pads, the plurality of N-designatedconductive pads and the plurality of lower electrically conductive leadsusing the layer of metal of the flexible metal clad by removing a metaloutside the plurality of third areas using the lower patterned mask;aligning a P-designated mask on top of the lower conduction layer of theflexible metal clad, wherein the P-designated mask has a first patterncorresponding to the plurality of P-designated conductive pads of thelower conduction layer, such that the plurality of P-designatedconductive pads are exposed through the P-designated mask; forming theplurality of P-type conduits with at least one layer of P-typethermoelectric material using the P-designated mask and at least onekind of P-type thermoelectric material, wherein each of the P-typeconduits is located on top of one of the P-designated conductive pads ofthe flexible metal clad exposed through the P-designated mask; aligningan N-designated mask on top of the lower conduction layer of theflexible metal clad, wherein the N-designated mask has a second patterncorresponding to the plurality of N-designated conductive pads of thelower conduction layer, such that the plurality of N-designatedconductive pads are exposed through the N-designated mask; forming theplurality of N-type conduits with at least one layer of N-typethermoelectric material using the N-designated mask and at least onekind of N-type thermoelectric material, wherein each of the N-typeconduits is located on top of one of the N-designated conductive pads ofthe flexible metal clad exposed through the N-designated mask.
 20. Themethod of claim 18: wherein each dielectric layer has a thermalconductivity value; wherein the internal dielectric layer is anelectrical insulator and a poor thermal conductor having the thermalconductivity value less than 1 watt per meter kelvin (W/(mK)), andwherein both the upper dielectric layer and the lower dielectric layerare electrical insulators and good thermal conductors having the thermalconductivity value greater than 5 watts per meter kelvin (W/(mK)).